Thermal anomalies during clear weather through March 2023; ash plume on 20 October 2022

Frequent weak-to-moderate ash explosions and lava flows have been recorded since the 19th century from three active craters at the summit of Langila, located on Papua New Guinea’s New Britain Island. The current eruption period began in October 2015; recent activity has included low-level thermal activity, ash emissions, and SO₂ plumes (BGVN 47:10). Similar low-level activity continued during October 2022-March 2023 based on information from the Darwin Volcanic Ash Advisory Center (VAAC) and satellite images.

The only completely clear Sentinel-2 image during the reporting period showed a single bright hotspot at the SE crater on 20 October, and thermal anomalies were visible on 4 and 7 November in two craters (figure 31). Persistent clouds prevented observations until another anomaly in one crater was visible starting on 28 January and on other clear days through March 2023. Gas-and-steam emissions rising from the crater were also sometimes present. The MIROVA hotspot detection system also recorded only a few scattered thermal anomalies during October 2022-March 2023 (figure 32), which cloud cover was common. The MODIS-MODVOLC thermal detection system did not record any hotspots during this time.

Figure 31. Sentinel-2 infrared satellite images of Langila showed a persistent hotspot in the SE crater and occasional wispy gas-and-steam emissions during October 2022-March 2023. A thermal anomaly is seen here from one crater on 20 October (top) and two craters on 4 November 2022 (bottom). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

Figure 32. The MIROVA hotspot detection system (Middle InfraRed Observation of Volcanic Activity) graph showed intermittent low-power MODIS thermal anomalies at Langila into mid-November 2022, one in early January 2023, and then more frequent detections in the second half of March 2023. Courtesy of MIROVA.

A single strong SO₂ plume was observed by the TROPOMI instrument aboard the Sentinel-5P satellite during the reporting period, on 26 October 2022. According to the Darwin VAAC, an ash plume rose 2.7 km in altitude, or 1.4 km above the summit, on 20 October and drifted NW. The plume dissipated within five hours.

Information Contacts: Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).

Information is preliminary and subject to change. All times are local (unless otherwise noted)

July 1973 (CSLP 96-73)

Lava emission from Crater 3 in mid-July

Card 1681 (20 July 1973) Lava emission from Crater 3 in mid-July

The eruption of lava from the No. 3 crater . . . commenced on 12 July 1973. There had been increased ash and steam emission during the preceding month. The lava flow was approximately 1 km long and 300 m wide by 18 July with lava still being extruded accompanied by loud rumblings. Only two other flows have been recorded this century, in 1960 and 1967. Both of these were small.

Information Contacts: O. Cooke, Volcanological Observatory, Rabaul, Papua New Guinea.

February 1974 (CSLP 96-73)

Large explosion from Crater 2 on 15 February

Card 1800 (19 February 1974) Large explosion from Crater 2 on 15 February

R. Cooke reported the following . . . via cable. "A large explosion occurred in Crater 2 . . . at 1000 on . . . 15 February. Volcanologists made an aerial inspection on . . . 17 February, and observed extensive modifications to internal details of Crater 2 and continuous light ash ejection from new funnel-shaped vent in Crater 2. At Crater 3 soft explosions were observed several times during the one-hour inspection.

"Activity since the previous event report consisted of slow, steady lava flow from Crater 3 for about six months from July 1973. This has apparently now ceased, although minor explosive activity occurring throughout this phase still occurs. A few soft ash ejections from Crater 2 occurred during this phase."

Information Contacts: R.J.S. Cooke, Volcanological Observatory, Rabaul, Papua New Guinea.

May 1978 (SEAN 03:05) Cite this Report

New mild Strombolian eruption

"Last year's mild Strombolian eruption at Crater 2 [NE crater] (figure 1 and 2) ended in mid-December, after a peak in early September during which a small amount of lava rose into the crater without overflowing. A new inner crater was blown through this lava a few weeks later and seems to have become considerably enlarged between aerial inspections on 21 March and 18 May. An unusually thick column of white vapor has been issuing from this crater during the last few weeks and a number of explosions were reported during May. A new mild Strombolian eruption [but see 3:9] from Crater 2 began 27-28 May and is continuing."

Figure 1. Sketch map of the NW tip of New Britain Island, showing Langila volcano and surrounding features. The portion of Langila's summit outlined by a box is shown in detail in figure 2. After Johnson and others (1971).

Figure 2. Summit area of Langila in 1970; the area shown is outlined in figure 1. From Palfreyman and others (1981).

Further References. Johnson, R.W., Davies, R.A., and Palfreyman, W.D., 1971, Cape Glouster Area, New Britain: volcanic geology, petrology, and eruptive history of Langila craters through 1970: Australian Bureau of Mineral Resources, Geology and Geophysics, Record no. 1971/14, 34 p.

Palfreyman, W.D., Wallace, D.A., and Cooke, R.J.S., 1981, Langila volcano: summary of reported eruptive history, and eruption periodicity from 1961 to 1972, in Johnson, R.W. (ed.), Cooke-Ravian Volume of Volcanological Papers; Geological Survey of Papua New Guinea Memoir 10, p. 125-133.

Information Contacts: R. Cooke, RVO.

September 1978 (SEAN 03:09) Cite this Report

Vulcanian activity; one or two large explosions/day

"An eruptive phase which began in late April and intensified markedly in late May has continued to the present (25 September). However, a volcanological party observed the activity from 30 May-9 June and found that it was not Strombolian as suggested by early reports, but Vulcanian in character. Typically, one or two larger explosions occurred per day, with a number of lesser ones. A lull was noted during mid-July and from late August. Since the first week of September, there has been little activity."

Information Contacts: R. Cooke, RVO.

October 1978 (SEAN 03:10) Cite this Report

Fewer explosions in October, but some larger than usual

Only six explosions were reported during October (7, 9, 11, 19, 25, and 29 October), but some were much larger than usual.

Information Contacts: R. Cooke, RVO.

December 1978 (SEAN 03:12) Cite this Report

Active lava dome; ash emission increases

The character of activity changed in late October, after six strong explosions had occurred earlier in the month. Explosions became more frequent, but only a little ash was present in the eruption clouds. Ash contents increased on 27 November and remained high through December while frequent explosions persisted. Since 27 November, a gray ash plume has been continuously visible over the volcano.

Aerial inspections on 7 and 15 December revealed an active lava dome in Crater 2 (Langila's NE crater). Incandescence was visible in the dome's surface fissures during these (daytime) overflights. Glow could be seen at night from 10 km away on 13 and 21 December.

Information Contacts: C. McKee, RVO.

January 1979 (SEAN 04:01) Cite this Report

Frequent ash ejection continues

Frequent ash ejection continued through January. Aerial inspections on 4, 15, and 29 January showed that the lava dome discovered in December has risen to the rim of Crater 2 without overflowing. By the end of January, a new craterlet had formed in the fresh lava surface.

Information Contacts: R. Cooke, RVO.

September 1979 (SEAN 04:09) Cite this Report

Ten loud explosions and ashfall

"For most of September the activity consisted of weak vapour emission accompanied by occasional small explosions. Only a very little ash was emitted. On 27 September a series of 10 loud explosions was accompanied by the emission of a dense ash cloud. A heavy ashfall occurred at Kilenge mission, 10 km NW of the volcano. No further details are yet available."

Information Contacts: R. Almond, RVO.

October 1979 (SEAN 04:10) Cite this Report

Occasional ash emission

"No further strong explosions have been observed since those of 27 September. The ash deposit from the 27 September explosions was several millimeters thick 10 km from the source. Grey ash clouds were seen on a few days at the beginning and end of October, and white vapour emissions were observed occasionally. Seismic activity remained at a low level."

Information Contacts: C. McKee, RVO.

November 1979 (SEAN 04:11) Cite this Report

Occasional ash emission

No ash emission was observed during the first half of November. Gray clouds were occasionally ejected from the 16th through the end of the month.

Information Contacts: C. McKee, RVO.

January 1980 (SEAN 05:01) Cite this Report

New crater formed

"A new crater was formed on the flank of Crater 3 on 19 January. Moderately thick brown/grey ash was explosively ejected until 20 January. Weak-moderate ash emissions resumed 24 January and continued intermittently until 29 January. Incandescence and rumbling were observed 28 January.

"During an overflight 28 January a brown-coloured deposit was observed extending up to 600 m from the new vent. Seismic activity consisted of numerous discrete volcanic events and possibly periods of tremor."

Information Contacts: B. Scott and C. McKee, RVO.

February 1980 (SEAN 05:02) Cite this Report

Lava effusion from new vent

"Sometime between overflights on 28 January and 15 February, effusion of lava commenced on the upper W flank of Crater 3, from the new vent formed on 19 January. When first observed on 15 February, the flow was about 700 m long. Explosions and rumbling were heard throughout the month, and glow and lava fragment ejections from the new vent were seen occasionally. Little ash emission was observed, but blue and white emissions were common. Crater 2 emissions consisted solely of white vapour.

"The seismograph was shifted from Kilenge Mission (10 km W of Langila) to Cape Gloucester airstrip (8 km N of the volcano) to enable joint direct visual and seismic observations. Seismic activity associated with the eruption was weak, consisting of tremor-like signals and probable explosion events."

Information Contacts: C. McKee, RVO.

April 1980 (SEAN 05:04) Cite this Report

Incandescent explosions continue

"Langila's eruption continued but observations have been prevented at times by poor weather. Incomplete reports for March indicated that incandescent explosive activity was continuing in the new crater, formed on 19 January. Blue and white vapour emissions from the new crater were commonly observed in April. Brown ash emissions were seen 9 and 10 April, and at night on those dates incandescent lava fragment ejections occurred. Crater glow was seen occasionally during the month, and rumbling and explosion sounds were heard daily. The 1980 lava flow appeared to have grown little since it was first seen on 15 February. Crater 2 usually emitted white vapour, and brown emissions were reported on 2 days in April. Explosive activity was expressed seismically as small discrete events that had the appearance of discontinuous tremor."

Information Contacts: C. McKee, RVO.

May 1980 (SEAN 05:05) Cite this Report

Eruption continues with tephra and small base surge; lava flow stops

"The eruption continued at moderate to low intensity. From the observation post about [10] km away, roaring, rumbling and detonations, were heard almost incessantly. Small Vulcanian explosions were occasionally observed from the active vent in Crater 3 (formed on 19 January).

"During a ground inspection on 8 May, detailed observation of several explosions revealed that blocks were commonly ejected to a height of about 600 m, accompanied by loud roaring. The concluding stages of explosions were characterized by streaming of translucent vapour followed by conspicuous emission of blue vapour. A larger explosion on 9 May produced a small base surge which traveled about 300 m W, leaving a pale brown deposit.

"The 1980 lava flow is blocky, and similar in hand specimen to lavas produced in the 1970's. The lava flow had ceased moving, and its length was about 800-1,000 m. Since it was first observed in February, three distinct lobes have entered adjacent valleys, the E lobe being the longest. A preliminary estimate of flow volume is 3 x 10⁵ m³."

Information Contacts: B. Scott and C. McKee, RVO.

June 1980 (SEAN 05:06) Cite this Report

Occasional explosions and glow

"Eruptive activity continued apparently without change during June. Light grey explosion clouds were occasionally observed rising from the active vent in Crater 3. Steady glow from this vent was observed on 5 June. Seismicity continued at the same intensity as previously."

Information Contacts: C. McKee, RVO.

July 1980 (SEAN 05:07) Cite this Report

Vulcanian explosions and glow

"Vulcanian explosions continued in July from the active vent at Crater 3, and crater glow was seen on several nights. Eruption clouds were usually brown/grey, but otherwise emissions were white and rarely blue. Emissions from Crater 2 were usually white, but possible ash contents in the emissions were reported on several days. Weak glow from Crater 2 was reportedly observed on one occasion. The level of seismic activity remained steady, and consisted of moderate-amplitude volcanic earthquakes, probably of explosion origin."

Information Contacts: C. McKee, RVO.

August 1980 (SEAN 05:08) Cite this Report

Occasional tephra emission

"The eruption continued at the same intensity in August. Emissions from the active vent in Crater 3 were mostly white and blue, but during a more active phase at mid-month grey emissions were observed. Lava fragment ejections and glows were observed on four consecutive nights 14-17 August. Rumbling and explosion sounds were heard on most days during the month. Crater 2 usually emitted white vapor, but on four occasions in the first half of August, brown emissions were observed. Glow at Crater 2 was observed on 4 August. The level and character of seismic activity was unchanged."

Information Contacts: C. McKee, RVO.

September 1980 (SEAN 05:09) Cite this Report

More frequent incandescent activity

"Observations of glow and lava fragment ejections from the active vent at Crater 3 were more numerous than in previous months. White and blue vapours were the common emission products, but grey emissions were seen on several days in the second half of September. Rumblings were heard throughout, occasionally augmented by explosive sounds. Occasional brown or grey emissions from Crater 2 were observed, but usually this vent released only white vapours. Seismic activity was reportedly unchanged."

Information Contacts: C. McKee, RVO.

October 1980 (SEAN 05:10) Cite this Report

Large explosions and block lava flow

"Langila was inspected between 1630 on 28 October and [0915] on 29 October, following reports of increased activity. Large Vulcanian explosions took place from Crater 2 at intervals of several minutes or more and produced dark grey convoluting ash clouds reaching heights of 3-5 km. Minor ejections of incandescent lava fragments also took place, producing impact craters to a distance of at least 200 m. Crater 3 contained a body of plastic incandescent lava that was upheaved frequently by Strombolian explosions. Incandescent lava fragments were ejected to 300 m in horizontal distance. The crater was topped by a pale grey emission cloud. A blocky lava flow [first noticed on 13 October] had advanced about 2 km on a broad front from Crater 3. The lava looked similar to previous flows, which have consisted of low-silica andesite. Seismic activity (volcanic tremor and B-type events) was greatly intensified in October, necessitating an increase in seismograph attenuation of 18 decibels."

Information Contacts: C. McKee, RVO.

November 1980 (SEAN 05:11) Cite this Report

Eruption declines

"Intensified eruptive activity that began in mid-October (05:10) continued until 8 November. Dark emission clouds continued to be released from Crater 2, and emission clouds from Crater 3 were pale grey. Ejections of incandescent lava fragments from both craters were accompanied by rumblings and explosion sounds. The lava flow from Crater 3 was reported to be still active on 11 November.

"A decline in the intensity of the eruption was evident on 8 November, when seismograph attenuation was reduced by 18 decibels. However, glows and ejections of incandescent lava fragments continued from both craters, and grey ash and vapour clouds continued to be emitted."

Information Contacts: C. McKee, RVO.

January 1981 (SEAN 06:01) Cite this Report

Lava flow and ash emission continue

"Vapour emissions continued from Craters 2 and 3. Some small ejections of brown-grey ash rose from Crater 2. The lava flow from Crater 3 was still active and had almost reached the terminus of the 1975 flow."

Information Contacts: B. Talai and P. Lowenstein, RVO.

March 1981 (SEAN 06:03) Cite this Report

Activity declines to vapor emission

"The first 3 months of 1981 have shown a steady decline of eruptive activity. Occasional brown ash-laden emissions from Crater 2 were observed in January, but in February and March emissions from Crater 2 were white and apparently of declining volume. Crater 3 released blue and white vapours in January and February; in March only small volumes of white vapour were emitted. The last time glow was observed was on 21 January from Crater 2. Seismic activity from Langila was at a low level January-March. Small tremor-like signals continued to be recorded."

Information Contacts: C. McKee, RVO.

April 1981 (SEAN 06:04) Cite this Report

Dark ash clouds and glow

"Eruptive activity, which had been declining since a peak in October 1980, increased in April. Explosions from Crater 2 produced dark ash clouds on 13 and 29 April. Weak glow above this crater was seen on 25 and 26 April. Pale grey emissions from Crater 3 were observed on 2, 14, 16, and 17 April. Blue emissions from the same vent were noticed on 8 days. No explosive sounds were detected at the observation post about 10 km away. The intensity of seismic activity remained low."

Information Contacts: C. McKee, RVO.

May 1981 (SEAN 06:05) Cite this Report

Weak ash emission

"On most days of observation, Crater 2 emitted white vapour, and brown or rarely grey ash in moderate volumes. Crater 3 released small volumes of white, blue, and occasionally grey emissions. No glows or lava fragment ejections from either crater were observed, and no volcanic sounds were heard."

Information Contacts: C. McKee, RVO.

June 1981 (SEAN 06:06) Cite this Report

Increased ash emissions, glow, lava fragments

"A further intensification of activity took place in June. Moderate to strong white and brown emissions from Crater 2 were commonly seen. Ashfalls were reported on several days from locations about 10 km from the volcano. Rumbling and/or explosive sounds were heard on most days. Crater glow or ejections of incandescent lava fragments from Crater 2 were seen on five days in the second half of the month. Crater 3 was less active, commonly releasing white or blue vapours, but weak grey emissions were occasionally seen. Seismic activity strengthened considerably. Large-amplitude, multiple explosion-type earthquakes and prolonged periods of tremor clearly represented tephra explosions and bouts of gas venting at Crater 2."

Information Contacts: C. McKee, RVO.

July 1981 (SEAN 06:07) Cite this Report

Vulcanian explosions and glow continue; seismicity intensifies

"Vulcanian explosions occurred at Crater 2 throughout July. Explosion and rumbling sounds were heard at an observation post about 10 km N of Langila. Brief aerial inspections on 16 and 20 July revealed that eruptions at Crater 2 were taking place at intervals of about 10 minutes. The maximum height reached by the eruption clouds was probably about 300-400 m. Glow from Crater 2 was seen on four consecutive nights, 25-28 July. Crater 3 was less active, usually releasing white and blue vapours in small volumes, but grey emissions were occasionally seen.

"The overall level of seismic activity intensified near the end of July, but its character remained similar to that observed in June. Periods of strong tremor were generated by explosions and prolonged gas jetting at Crater 2."

Information Contacts: C. McKee, RVO.

August 1981 (SEAN 06:08) Cite this Report

Ash and incandescent tephra ejection, then explosions and seismicity decline

"Eruptive activity at Crater 2 declined near the middle of August; frequent Vulcanian explosions and periods of ash emission gave way to white and blue vapour emission occasionally punctuated by intervals of brown or grey ash emission. Ashfalls were noted at coastal locations about 10 km N and NW of the volcano until 14 August. Ejections of incandescent material were seen on 6, 7, 8, and 14 August. Sounds of detonations, rumbling, and roaring were heard during the first half of the month. Crater 3 released white vapours throughout August, and blue emissions were seen rarely in the second half of the month. Seismic activity declined from a peak reached near the end of July, but the character of the activity was unchanged."

Information Contacts: C. McKee, RVO.

September 1981 (SEAN 06:09) Cite this Report

Ashfalls; incandescent tephra; discontinuous tremor

"Ash emission from Crater 2 resumed near the beginning of September after about two weeks of mainly white and blue vapour emission in late August. Significant ashfalls occurred W and N of the volcano, particularly in the first three weeks of September. Glow and ejections of incandescent lava fragments from Crater 2 were occasionally observed, and rumbling and explosion sounds were heard throughout the month. Crater 3 activity continued to be weak, consisting of weak emissions of white vapour.

"Seismicity fluctuated in strength. Several seismic events had the appearance of Vulcanian explosion earthquakes (from Crater 2), but the main feature of the seismicity in September was prolonged periods of discontinuous tremor, probably representing periods of ash emission. Frequent small brief seismic events began to be recorded at mid-month."

Information Contacts: C. McKee, RVO.

October 1981 (SEAN 06:10) Cite this Report

New lava flow, incandescent tephra, ash emission

"Eruptive activity intensified in October when Crater 3 became strongly active, emitting incandescent tephra and a new lava flow. After a brief interval of ash emission on 3 October, Crater 3 began a sustained period of explosive activity on 9 October. Ejections of incandescent tephra were seen on 15 October and continued from 17 October throughout the month. The production of a new lava flow from Crater 3 was suspected on 27 October and confirmed on the 28th. The flow rate was apparently low.

"Activity at Crater 2 may have declined since late September. Vulcanian explosions occurred at intervals of several days, and periods of less-explosive ash emission were observed at the beginning and end of October. At other times, Crater 2 released white and blue vapours. Crater 2 glow was observed on 1, 3, 17, and 18 October.

"Ashfalls were reported in inhabited areas about 10 km N and W of the volcano on about 50% of days during the first half of October. Seismicity remained at a fairly low level, consisting mainly of numerous small events probably originating from Crater 3."

Information Contacts: C. McKee, RVO.

November 1981 (SEAN 06:11) Cite this Report

Eruption column to 6-7 km altitude; nuées ardentes

"Strong eruptive activity continued in November. The present eruptive episode is the most intense since October-November 1980 (05:10-11). Detailed observations were made by a volcanologist 17-26 November.

"Crater 2 produced a wide variety of activity. Vulcanian explosions rising to about 2 km were commonly observed. Frequency of explosions varied from minutes to hours, and periods of near-continuous (Strombolian) activity were also noted. Crater 2 glow was seen during the first half of the month, followed by apparently more intense activity including ejections of incandescent tephra occasionally rising to 0.5 km above the source. Commonly the larger Crater 2 explosions registered a seismic airwave. Rumbling and detonations from Crater 2 were heard throughout the month.

"Small nuées ardentes were produced by backfall of ejecta from some of the Crater 2 explosions. The largest of the nuées traveled about 2 km down the E flank. Periods of continuous harmonic tremor appeared to be related to resonance effects in the Crater 2 lava conduit. Continuous fluctuating glow, incandescent tephra ejections, and associated rumbling and booming sounds were noted from Crater 2 during some of the periods of harmonic tremor.

"Crater 3 activity may have declined during the month. Incandescent tephra ejections or crater glow were common during the first half of the month, but only occasionally observed later in November. Several large Vulcanian explosions were observed. One on 13 November was reported by a passing aircraft pilot as rising to about 6-7 km altitude, and having a columnar appearance. Crater 3 eruptions later in the month were often single events. Some were accompanied by loud detonations and others were soundless. Some of the soundless eruptions were registered seismically as large-amplitude, low-frequency events.

"The new lava flow from Crater 3 appeared to become inactive in mid-November. The flow rate was evidently low, as only a small volume of lava was extruded during the 2-week period of lava effusion."

Information Contacts: P. Lowenstein and C. McKee, RVO.

December 1981 (SEAN 06:12) Cite this Report

Strong explosions continue; incandescent tephra

"Strong eruptive activity continued during December although a decline was apparent in the last week of the month. Activity was centred at Crater 2, which produced dark brown or dark grey tephra emissions throughout December. On several days in the first half of the month the emissions were reported as being thick. Significant ashfalls at inhabited areas about 10 km to the N and W occurred 6, 8-12, 14, 17, 22, and 29 December. Sounds of explosions and rumbling were heard 1-14 December, and detonations were frequent 9-10 and 15-17 December. Incandescent tephra ejections or crater glow were seen 1-4, 8, 13-18, and 20 December. Dark emissions from Crater 3 were observed once (on 1 December); otherwise, the only products from this crater were white and blue vapours. Seismic activity showed a good correlation with visible activity. Periods of stronger visible activity were usually accompanied by large-amplitude volcanic earthquakes and periods of harmonic tremor."

Information Contacts: C. McKee, RVO.

January 1982 (SEAN 07:01) Cite this Report

Vulcanian and Strombolian activity; lava flow

"Occasional Vulcanian explosions from Crater 2 were reported. One explosion on 11 January was accompanied by a loud detonation, and an associated earthquake was felt 10 km away. Crater 2 glow was seen on 14 and 16 January.

"From 1-17 January, Crater 3 produced white and blue emissions. From the 18th pale grey Strombolian eruption clouds were seen. Rumbling and explosion sounds were associated with these eruptions. Crater 3 glow or ejections of incandescent tephra were seen beginning then. An active lava flow from Crater 3 was first observed 21 January.

"Seismicity recorded 11-23 January contained large-amplitude Vulcanian explosion shocks originating from Crater 2, and other smaller scale activity which probably originated at Crater 3. The apparent Crater 3 seismicity consisted of numerous, brief, small-amplitude events 14-17 January, and larger amplitude tremor envelopes 18-23 January which probably were an expression of the visible Strombolian eruptive activity that commenced 18 January."

Information Contacts: C. McKee, RVO.

February 1982 (SEAN 07:02) Cite this Report

Vulcanian activity; glow and incandescent tephra

"Both craters produced occasional Vulcanian explosions during February. Activity appeared to be stronger in the first half of the month. Explosions from Crater 3 rose to 3-4 km on 9 and 11 February, and from Crater 2 to 6-7 km on the 13th and 14th. Glow and incandescent tephra ejections were observed at Crater 2 most nights the first half of the month, occasionally the second half. At Crater 3 incandescent tephra emission was reported only on 7 February.

"The main feature of February seismicity was the registration of several Vulcanian explosion earthquakes per day. Larger events were recorded 8-17 February. Two periods of frequent, brief, small-amplitude seismic events occurred 6-9 and 13-16 February. This activity became more intense on the 14th and 15th, giving rise to signals resembling discontinuous seismic tremor."

Information Contacts: C. McKee, RVO.

March 1982 (SEAN 07:03) Cite this Report

Incandescent tephra; increased seismicity

"A fairly low level of activity prevailed in early March, but in the second half of the month activity at both craters intensified. Crater 3 erupted incandescent tephra 18-22 March, accompanied by frequent explosive detonations and loud rumbling. From 22 March until the end of the month glow and incandescent tephra ejections from Crater 2 were seen on most nights. Dark eruption clouds were occasionally seen, and loud explosions and rumblings were heard. Seismicity was stronger from 18 March, and correlated with the intensified visible activity."

Information Contacts: C. McKee, RVO.

April 1982 (SEAN 07:04) Cite this Report

Incandescent tephra; ashfalls; seismicity

"A steady level of mild eruptive activity prevailed at Crater 2 during the first part of April. Distinctly stronger activity was evident on the 23rd. Eruption clouds became more heavily charged with tephra, audible explosions more intense, and ejections of incandescent lava more frequent. Activity at Crater 3 was subdued, consisting usually of weak emissions of white and rarely grey vapour, and occasional emissions of blue vapour. Relatively small explosions producing dark brown or grey tephra clouds were observed on 15 and 26 April. Ashfalls at the observation post, about 10 km N of the craters, occurred on 15, 20, 25, and 30 April. Seismicity was steady at moderate to low levels during the first half of April, but intensified on the 20th. The increased seismicity was directly associated with the stronger visible explosive activity at Crater 2."

Information Contacts: C. McKee, RVO.

May 1982 (SEAN 07:05) Cite this Report

Explosive activity, lava flow and ashfalls

"Following a period of moderately intensified explosive activity from Crater 2 in the second half of April, strong eruptive activity took place from this vent 2-16 May. During peak activity, 5-9 May, strong Strombolian activity was observed. Frequent ejections of bright red incandescent lava to maximum heights of 250-300 m above the crater were seen. An eruption column rose to about 4 km on 6-7 May. Ashfalls were experienced in inhabited areas about 10 km N and NW of the volcano during most of the first half of the month. The total thickness of these deposits was probably several millimeters.

"A significant event in this phase of Crater 2 activity was the production of a substantial lava flow. Several lobes developed NE of the crater, the largest extending to about 1 km in length. The volume of the flow is estimated to be 0.5-1.0 x 10⁶ m³. Occasional Vulcanian explosions took place 17-31 May at Crater 2, and crater glow was seen once, on the 19th. Throughout the month Crater 3 emitted white and blue vapours at a low rate.

"Seismicity corresponded closely with the intensified visible activity. During the peak eruptive period seismic tremor was produced by the Strombolian explosive activity. As eruption intensity waned, discrete earthquakes associated with Vulcanian explosions at Crater 2 became prominent."

Information Contacts: B. Talai and C. McKee, RVO.

July 1982 (SEAN 07:07) Cite this Report

Activity declines to occasional Vulcanian explosions

"Following a strong eruption from Crater 2 in early May, activity declined sharply. From about 17 May occasional Vulcanian explosions took place at this crater, but usually the only emissions were white vapours and occasionally blue vapours in small volumes. Ashfalls were reported 10 km N of the crater at the beginning of June and on 8, 10, and 31 July.

"Crater 3 has shown declining activity since April when occasional explosions were seen. Weak white and blue emissions were seen until about mid-June, but since then the crater has been completely inactive except for weak white vapour emissions on 18 July. Seismic activity has remained low since mid-May."

Information Contacts: C. McKee, RVO.

August 1982 (SEAN 07:08) Cite this Report

Explosive eruptions; ash to six kilometers

"A resurgence of activity was evident in August as Vulcanian explosions from Crater 2 became more common. Explosive eruptions occurred on 5, 12, 14, 15, 17, 24, and 31 August, and light ashfalls were experienced at the observatory post 10 km to the N after most of these eruptions. The cloud from the largest explosion, on 15 August, reached a height of about 6 km. Crater 3 continued to show little or no activity. Seismic activity generally remained low, although earthquakes associated with the Vulcanian explosions were recorded."

Information Contacts: C. McKee, RVO.

September 1982 (SEAN 07:09) Cite this Report

Vulcanian explosions; ash emissions

"Activity in September was similar to that seen in August. However, Crater 2 showed a more intense phase of activity in the second half of the month which included more frequent Vulcanian explosions and periods of continuous ash emission. Light to moderate ashfalls at the observation post 10 km N of the volcano were recorded on 5 days but mostly in the second half of the month. No crater incandescence was seen. Blue vapour emissions from Crater 2 were observed on several days at the beginning and end of the month.

"Crater 3 showed little or no activity apart from weak emissions of white-grey vapour. The greyish color is not considered to be caused by entrained ash but to be an effect of peculiar light conditions [during early-morning periods of observation].

"Seismicity was generally at a low level, although explosion earthquakes were associated with the Vulcanian activity at Crater 2."

Information Contacts: C. McKee, RVO.

October 1982 (SEAN 07:10) Cite this Report

Vulcanian explosions; ashfalls; glow

"The level of activity in October was similar to that observed in September. Grey and brown ash emissions from Crater 2 were seen on about 50% of days; otherwise, white vapours were emitted. Ashfalls in areas about 10 km from the volcano were reported on 4, 5, and 6 October. Vulcanian explosions were observed on 7 and 30 October. On the 7th a dark brown eruption column rose to about 3.5 km, and incandescent ejecta started fires in vegetation at the foot of the volcano. The explosion on the 30th was much smaller, the ash column rising only a few hundred meters. Crater 2 was more active from the 22nd. Crater glow was seen on 22, 24, and 25 October, and weak to strong rumbling sounds from the crater were heard on 22, 23, 24, 26, and 29 October.

"Crater 3 continued its low level of activity, releasing white and blue vapours in small volumes. Seismic activity remained at a low level. A few Vulcanian explosion earthquakes were recorded."

Information Contacts: C. McKee, RVO.

November 1982 (SEAN 07:11) Cite this Report

Two large Vulcanian explosions

"A generally low level of activity prevailed during November, when both craters usually emitted tenuous white vapours, and usually no crater incandescence or sound effects were observed. However, two large Vulcanian explosions from Crater 2 were reported, on 12 and 22 November. A dense ash cloud was erupted at about 1930 on the 12th. Brilliant lightning displays were reported, and the eruption cloud contained incandescent tephra. On the 22nd a 3 km-high eruption column was produced by an explosion at about 0200. Light ashfalls 10 km N and W of the volcano were reported. Seismic activity was generally low, although several explosion earthquakes were recorded.

"A detailed aerial and ground inspection was carried out on 29 November. Both craters were releasing thin white and blue vapours. At the S rim of Crater 2 a strong odour of SO₂ was detected. The strong eruptive activity at Crater 2 in May resulted in significant accumulation (about 100 m) of coarse red-brown tephra mainly on the W rim of the crater. Vulcanian explosions since then have reamed out a funnel-shaped crater 250-300 m wide and about 200 m deep. No vents were visible in the floor of the crater. Crater 3 was about 150 m across and shallow, and most emissions seemed to originate from sources scattered around the crater walls. The nose of the westernmost lobe of the May Crater 2 lava flow was visited. The flow thickness at that point was about 20 m."

Information Contacts: C. McKee and P. Lowenstein, RVO.

December 1982 (SEAN 07:12) Cite this Report

Increasingly violent Vulcanian eruptions

"Activity increased in December. Crater 2 produced thick white emissions while Crater 3 released white or blue vapours. Seismicity was generally low. Vulcanian explosions of increasing violence occurred from Crater 2 on 1, 14, 16, 25, and 26 December. On these occasions, the development of a dark grey ash-laden column up to 9 km was accompanied by loud rumbling noises and explosion earthquakes, and followed by light ashfalls. On 16 and 26 December harmonic tremor accompanied the subsequent escape of gases and tephra. The large explosion on the 26th at 1400 was accompanied by vivid lightning, ejected incandescent boulders up to 2 km from the crater, and started bush fires on the NW flank of the volcano. Twenty explosion shocks were recorded over the background tremor during a 25-minute period after the eruption, and Crater 2 remained incandescent for 45 minutes."

Information Contacts: P. de Saint Ours and P. Lowenstein, RVO.

January 1983 (SEAN 08:01) Cite this Report

Several Vulcanian explosions per day

"Volcanic activity increased markedly in January and was concentrated in Crater 2. Several Vulcanian explosions were recorded every day. The most violent, 11-14 and 22-24 January, ejected incandescent boulders and tephra, illuminating the dark ash-laden column and setting fire to vegetation on the volcano's flanks. Consecutive ashfalls were blown SE over unpopulated areas. Crater 3, meanwhile, was quietly exhaling weak white vapours. In the sub-continuous seismic background, each discrete explosion was recorded as a sharp, large-amplitude event with a period of 1.5 Hz."

Information Contacts: P. de Saint Ours and B. Talai, RVO.

February 1983 (SEAN 08:02) Cite this Report

Explosions build to 6-day Strombolian-Vulcanian event

"The increased Vulcanian activity of Crater 2 in January culminated in a rise of the magma column, with an eruptive phase maximum 11-16 February. The 3-11 February buildup of the eruption consisted of approximately hour-long periods of loud rumbling noises, with deep explosion sounds at 5-30 second intervals. Several times per day at irregular intervals, individual explosions produced black ash-laden columns that rose as much as 3-4 km before being dissipated by the NW winds. Night glow, observed 3 February, became more intense during this period. Low Strombolian fountaining was visible 3-5 and 9 February.

"During the six days of maximum activity, Crater 2 simultaneously displayed continuous Strombolian fountaining to 100 m and intermittent powerful Vulcanian explosions. Most of the Vulcanian explosions were laterally directed, while the continuous moderate vapour emissions and Strombolian fountaining were central and vertical, leading to the conclusion that Crater 2 may contain two more or less independent vents.

"Seismic activity consisted of a sub-continuous background of harmonic tremor and Strombolian B-type earthquakes. Each individual Vulcanian eruption produced large-amplitude low-period explosion events. The most powerful explosions occurred 12-13 and 15 February at the rate of 2-5 per hour.

"During the eruption, Crater 3 (a separate composite cone 300 m W of Crater 2) released only weak white vapours. However, the volume of emission increased to moderate or large during the first 10 days of February, the time of the activity buildup at Crater 2."

Information Contacts: P. de Saint Ours and P. Lowenstein, RVO.

March 1983 (SEAN 08:03) Cite this Report

Activity declines

"After the increased explosive activity from Crater 2 in February, the level of activity returned to normal. White-grey vapour and ash emissions were seen on a few days, and occasional relatively small Vulcanian explosions were observed. Explosion and rumbling sounds were heard occasionally. The only volcano-seismic activity recorded was from Vulcanian explosions at Crater 2 which occurred at intervals of a few hours to about 4 days."

Information Contacts: C. McKee, RVO.

April 1983 (SEAN 08:04) Cite this Report

Six explosions, highest cloud to 8 km

"A generally low level of activity prevailed during April. However, Crater 2 produced some discrete Vulcanian explosions (table 1). The explosion on the 18th was witnessed from an aircraft about 70 km away. The eruption cloud rose steadily for about 15 minutes, then began spreading at its top to become mushroom-shaped. Weak emissions of grey ash clouds were also reported on 8, 14, 20, 21, and 29 April. Crater 3 was quiet for most of the month, releasing weak white vapour, although grey emissions were reported on 21 and 26 April. On the 30th a Vulcanian explosion sent ash and vapour to a height of about 3 km. Seismic activity was generally at a low level, with occasional explosion earthquakes."

Table 1. Heights of Vulcanian explosion columns above Crater 2 at Langila, April 1983.

Information Contacts: C. McKee, RVO.

May 1983 (SEAN 08:05) Cite this Report

Moderate Vulcanian activity, one plume to 7 km

"A generally steady moderate level of Vulcanian explosive activity prevailed in May. On most days when the summit was clear, pale grey or brown emissions were reported from Crater 2. Vulcanian eruption columns rose to about 300 m on 16 May, and 7 km on 17 May. Explosion or rumbling sounds were heard on about 60% of days. Weak glow from Crater 2 was seen on 4 nights: 8, 11, 13, and 25 May. Crater 3 continued to show very mild activity, usually releasing thin white vapours and rarely emitting pale grey clouds.

"Volcano seismicity consisted of occasional Vulcanian explosion earthquakes at an average rate of several per day. On 3, 5, and 16 May explosion earthquakes were followed by periods of about 30 minutes of tremor probably produced by prolonged powerful degassing at Crater 2."

Information Contacts: C. McKee, RVO.

June 1983 (SEAN 08:06) Cite this Report

More frequent Vulcanian explosions

"Activity increased somewhat in June as Vulcanian explosions became more frequent. Ash emissions from Crater 2 were observed on most days and Vulcanian explosions usually occurred at rates of 0-5 per day. However, two periods of more intense activity took place; 4-17 June, and starting 26 June and continuing at month's end.

"In the first period of stronger activity, rates of recorded Vulcanian explosions reached about 30 per day on 7 June, and about 15 per day on 8 and 10-14 June. Weak red glow from Crater 2 was seen on the nights of 10 and 11 June. Light ashfalls were reported from about 10 km W of the crater.

"In the second period of stronger activity, from 26 June onwards, ash emissions from Crater 2 became more frequent, and sounds of detonations and rumbling more noticeable. Ejection of incandescent tephra was seen the night of 26 June, and continuous glow was observed early on the morning of the 27th. In the last few days of the month the volcano was obscured by the ash emissions from Crater 2. Ashfalls of several mm were reported at locations 10 km N and W of the volcano.

"Crater 3 continued to show a low level of activity, usually releasing tenuous white vapours. However, thick dark brown ash clouds were emitted on 6 June, and pale grey emissions were reported on 12 June. Volcano seismicity at Langila was dominated by the earthquakes produced by Vulcanian explosions."

Information Contacts: C. McKee, RVO.

July 1983 (SEAN 08:07) Cite this Report

Explosions; ashfalls; strong harmonic tremor

"Stronger activity that commenced at Crater 2 on 26 June continued into July. During the first week of July, ash emissions blown down the volcano's flanks by strong winds occasionally obscured the active vent. A few large Vulcanian explosions were observed, and associated detonations and rumblings were heard frequently at the beginning of the month. Ashfalls continued during this period in inhabited coastal areas about 10 km to the NW and N. Weak crater glow was noted on 2 July.

"Seismic records indicate an average of about five Vulcanian explosions per day in the first week of July, accompanied by large-amplitude harmonic tremor on most days. A decline in activity was evident after 7 July as emissions became less voluminous and less ash-rich, and explosive sounds less frequent.

"Activity re-intensified somewhat from 15 July. Greater quantities of ash were ejected, resulting in renewed ashfalls in coastal areas. On a few days the volcano was again obscured by its own ash emissions. Vulcanian explosions continued to register on seismograms at an average of about 3 per day.

"Crater 3 remained relatively inactive, mainly releasing white vapours. However, pale grey and blue emissions were reported on 9 July.

Information Contacts: C. McKee and P. de Saint Ours, RVO.

August 1983 (SEAN 08:08) Cite this Report

More, stronger explosions; ashfalls to 10 km

"A definite strengthening of Vulcanian activity at Crater 2 has been observed since late June. This phase of activity is the strongest since January-February.

"On most days in August ash-laden vapour emissions from Crater 2 were blown down the volcano's flanks by strong winds, obscuring both the active vent and Crater 3. Strong activity in the first 8 days of the month consisted of up to 15 Vulcanian explosions per day, and periods of harmonic tremor recorded 4-8 August. Light to moderate ashfalls were common in coastal inhabited areas about 10 km NW and N. A decline of activity was observed 9-20 August as emissions became less voluminous and less ash-rich, and sound effects were heard less frequently. Occasional explosion earthquakes were recorded. More frequent Vulcanian explosions, loud sound effects, and ashfalls resumed on 21 August.

"In contrast to activity in January and February 1983, when incandescent lava ejections took place, the more explosive activity at Crater 2 in August was rarely accompanied by incandescence. Weak crater glow was observed on only 2 nights (17 and 29 August). Crater 3 remained relatively inactive, usually releasing thin white vapours."

Information Contacts: C. McKee and P. de Saint Ours, RVO.

September 1983 (SEAN 08:09) Cite this Report

Explosions, tremor from gas venting; glow seen twice

"Explosive eruptive activity continued at Crater 2, and was stronger 2-6 September. Up to 12 explosions per day were recorded, and periods of strong volcanic tremor were produced by prolonged gas venting. Activity declined 8-11 September, but re-intensified on the 12th. Moderate activity persisted for the remainder of the month, including patchy and weak tremor and 1-9 explosions per day. Weak red glow was observed over Crater 2 on 25 and 29 September. Light to heavy ashfalls were common in coastal inhabited areas about 10 km to the NW and N."

[Richard Stoiber, Stanley Williams, and Chris McKee used a COSPEC to measure the rate of SO₂ emission from several volcanoes in Papua New Guinea during September (table 2). Plumes at and Manam were strong, and plume was small. Activity at Langila was weak 11 September, but had intensified during measurements the next day. The quiet-phase data were collected from the ground; all other data were acquired while flying under the plumes.]

Table 2. Rates of SO₂ emission at Bagana, Langila, Manam, and Ulawun, Papua New Guinea, September 1983. Airborne COSPEC data from R. Stoiber, S. Williams, and C. McKee.

Information Contacts: C. McKee, RVO; R. Stoiber and S. Williams, Dartmouth College.

October 1983 (SEAN 08:10) Cite this Report

Moderate Vulcanian activity; explosion events; tremor

"Moderate explosive activity persisted at Crater 2 during the first week of October, but from the 8th until the end of the month, eruptive activity was at a low level.

"During 1-7 October, activity at Crater 2 consisted of weak-strong ash emission accompanied by explosion and rumbling sounds heard 10 km away. Weak red night glow from the crater was observed 3-7 October. Seismically this activity was represented by occasional large Vulcanian explosion earthquakes (2-5 per day), numerous smaller explosion shocks, and rare periods of continuous and discontinuous harmonic tremor. Ashfall was experienced in coastal inhabited areas about 10 km N and NW of the volcano on 2 October.

"From the 8th until the end of the month, Crater 2 released white emissions in small to moderate quantities. However, Vulcanian explosions accompanied by loud detonation sounds and ejections of incandescent material took place on 24 and 27 October. Seismicity was at a low level 8-31 October, but rare Vulcanian explosion events were also recorded. Crater 3 released small volumes of white and occasionally blue vapours throughout the month."

Information Contacts: C. McKee, RVO.

December 1983 (SEAN 08:12) Cite this Report

Tephra to 2.7 km height; small lava flow

"Vulcanian activity continued from Crater 2 with a pronounced increase toward the end of the month that culminated in the production of a small lava flow on the NE flank.

"From 1-20 December, activity consisted of occasional emissions of white-grey tephra rising to 0.6-1.2 km above the summit, accompanied by weak to low rumbling noises and explosions. Glow was visible 12-14 December, with ejection of glowing fragments to 270 m on the 13th. Fine ashfalls occurred 10 km to the N on 6, 7, 11, and 15 December.

"From 21-27 December, activity became much stronger, with continuous ejection of thick tephra-laden vapour to 1.8-2.7 km above the summit accompanied by continuous loud rumbling and explosion sounds. Continuous glow and ejections of lava fragments were observed at night with overflow of lava to the NE 23-28 December. This was accompanied by long periods of continuous harmonic tremor which increased in amplitude during the periods of maximum activity. Crater 3 remained inactive throughout, with only weak emissions of white vapour."

Information Contacts: P. Lowenstein, RVO.

January 1984 (SEAN 09:01) Cite this Report

Vulcanian explosions; ashfalls on coast

"Activity remained high at Crater 2, but Vulcanian explosions replaced the more continuous activity that produced the lava flow on the NE flank in December. For most of the time, Crater 2 produced moderate amounts of white to brown ash-laden vapour, accompanied by discontinuous rumbling and explosion sounds, while the seismic station at Cape Gloucester airstrip, 9 km away, recorded discontinuous tremors and large explosion earthquakes. Peaks of activity occurred on 7, 12, and 25 January with emission of columns of thick dark tephra-laden vapour to heights of 1.5-2.5 km above the crater. Large blocks were ejected as far as 2 km from the vent by the more powerful explosions, and ashfalls were experienced on the coast, 10 km downwind. Activity at Crater 3 was confined to the emission of white and blue vapours."

Information Contacts: P. Lowenstein, RVO.

February 1984 (SEAN 09:02) Cite this Report

Activity declines; one Vulcanian explosion

"Activity was substantially reduced during February. The main activity at Crater 2 was the release of white vapours and rarely pale grey ash clouds. One Vulcanian explosion was observed on 7 February, producing a thick dark ash cloud that rose about 3 km above the vent. Crater glow was seen on 3 and 5 February. Crater 3 continued its usual activity of weak to moderate white and blue vapour emission. Seismicity was at a low level, with only a few recorded explosion earthquakes."

Further Reference. Johnson, R.W., 1984, Volcanological inspections in Papua New Guinea, February 1984: Geological Survey of Papua New Guinea Report 8/84.

Information Contacts: C. McKee, RVO.

March 1984 (SEAN 09:03) Cite this Report

Activity low; explosions at middle and end of month

"A relatively low level of activity persisted during March, although a slight intensification was noted after the 19th. Pale grey ash emissions from Crater 2 were occasionally observed 1-18 March. A strong Vulcanian explosion took place on 19 March, and on the 20th further explosions were observed. The seismic record for 20 March indicates a total of 10 explosions. A lull in Crater 2 activity was noted 21-25 March but weak ash emission began on the 26th, and explosive activity resumed on the 27th. Two or three explosion earthquakes were recorded on 27, 28, and 30 March. Crater 3 released white and blue vapours at low rates throughout the month."

Information Contacts: C. McKee, RVO.

April 1984 (SEAN 09:04) Cite this Report

Occasional Vulcanian explosions for 10 days

"For most of April, activity was at a low level with weak to moderate white and occasionally grey emissions from Crater 2, and weak white and rarely blue emissions from Crater 3.

"However, between 7 and 17 April stronger activity took place at Crater 2. Occasional strong Vulcanian explosions producing eruption columns up to about 5 km high were accompanied by detonations and rumblings, and ashfalls were recorded in coastal areas 10 km to the N and NW. Characteristic impulsive earthquakes also accompanied these explosions."

Information Contacts: C. McKee, RVO.

May 1984 (SEAN 09:05) Cite this Report

Intermittent ash emission; three Vulcanian explosions

"Activity in May was similar to that in April. Intermittent weak-moderate ash emissions from Crater 2 were reported during the first 8 days of May. During the remainder of the month Crater 2 usually released white vapours at low rates. However, strong Vulcanian eruptions accompanied by loud detonations took place on 13, 25, and 28 May. These eruptions resulted in reportedly heavy ashfalls 10 km downwind. Weak emissions of white and blue vapours continued at Crater 3."

Information Contacts: C. McKee, RVO.

June 1984 (SEAN 09:06) Cite this Report

Occasional ash emission; seismicity weak

"Activity was generally very weak at both craters in June. The emissions were usually white or occasionally blue vapours. However, lightly ash-laden clouds were emitted from Crater 2 on 16-18 and 21 June. Seismicity was at a very low level throughout, with occasional low-amplitude volcanic earthquakes."

Information Contacts: C. McKee, RVO.

August 1984 (SEAN 09:08) Cite this Report

Occasional ash emission; seismicity weak

"Activity remained at the generally low level that has persisted for several months. Occasional grey or brown ash emissions from Crater 2 were reported. Seismicity was at a very low level throughout, with only occasional small volcanic earthquakes."

Information Contacts: C. McKee, RVO.

November 1984 (SEAN 09:11) Cite this Report

Occasional ash emission; seismicity low

"For the period September to November, activity remained at a low level. Occasional grey or brown ash emissions from Crater 2 were reported. Seismicity was at a very low level with only a few volcanic earthquakes recorded."

Information Contacts: C. McKee, RVO.

February 1985 (SEAN 10:02) Cite this Report

Ash clouds and glowing tephra mark new eruptive phase

"Activity intensified in February after being at a very low level for about 1 year. Several large Vulcanian explosions at Crater 2 in late January marked the commencement of this new eruptive phase. Explosions occurred at rates of up to about 20 per day in February. The largest explosions produced eruption columns reportedly about 3-4 km high. No significant ashfalls took place in inhabited areas. Weak glow was frequently observed from Crater 2 up to about mid-February, and ballistic incandescent lava fragments were seen at the bases of some eruption columns. Seismicity accompanying this activity not only included the usual discrete explosion earthquakes, but also a number of periods of harmonic tremor, thought to be caused by sequences of prolonged gas discharge at Crater 2. Crater 3 remains inactive, except for mild fumarolic activity from the crater walls."

Information Contacts: C. McKee, RVO.

March 1985 (SEAN 10:03) Cite this Report

Return to low level of activity

"Langila returned to a low level of activity in early March after a period of moderate-to-strong explosive activity at Crater 2 in February. From 3 March, activity at Crater 2 usually consisted of weak emission of white vapour, although occasional Vulcanian explosions took place. Crater 3 remained quiet."

Information Contacts: C. McKee, RVO.

June 1985 (SEAN 10:06) Cite this Report

Ash emission and glow mark new phase of activity

"A new phase of increased activity at crater 2 began about 8 June. This followed several months of very weak activity punctuated by occasional mild Vulcanian explosions. From mid to late May a more prolonged period of slightly intensified activity consisted of grey ash emissions, occasional explosion sounds, and several periods of crater incandescence.

"Rumbling and explosion sounds, large quantities of blue vapor, and occasional grey ash clouds were reported from crater 2 between 8-12 June, marking the onset of a new phase of activity. A further intensification took place mid-month and an eruption column about 1 km high was reported on the 17th. Weak glow from crater 2 was observed on the night of the 20th, and explosion sounds were more frequently heard on the 22nd. Light ashfall was reported 10 km downwind on the 27th. Seismicity was comprised of characteristic Vulcanian explosion earthquakes. This higher level of activity was continuing at the end of June."

Information Contacts: C. McKee, RVO.

July 1985 (SEAN 10:07) Cite this Report

Stronger Vulcanian explosions

"Further intensification of the eruption at Crater 2 took place in July. Increased activity was noticeable from 19 July when the frequency of Vulcanian explosions increased from about 2 to 10 per day. These explosions were stronger, as indicated by ashfalls as far as 10 km downwind, louder detonations, and rumbling. Incandescent lava fragments were ejected on the night of 19 July. A further increase in activity was apparent from 22 July when daily totals of Vulcanian explosions climbed to about 30 and periods of continuous harmonic tremor were recorded."

Information Contacts: C. McKee, RVO.

August 1985 (SEAN 10:08) Cite this Report

Two episodes of explosions, earthquakes and tremor

"The stronger eruptive activity reported in late July declined rapidly at the beginning of August, but this was followed by two more spasms of intensified activity. More frequent Vulcanian explosions from Crater 2, accompanied by characteristic volcanic earthquakes and sequences of continuous harmonic tremor, took place 10-14 and 19-23 August. Weak red incandescence at the crater was observed from locations about 10 km downwind on 10 and 11 August."

Information Contacts: C. McKee, RVO.

September 1985 (SEAN 10:09) Cite this Report

Stronger explosions; ashfall to 30 km

"Activity intensified in September. A moderate phase of eruption began on 6 September when an ashfall was noted at Kilenge Mission (10 km NW of Langila). From 9 to 13 September, incandescence was noted at Crater 2 and there was an increase in audible explosions and rumblings (heard at the observation post, 10 km NW). Small incandescent ejections were reported on the night of 9 September. Seismic tremor lasting from a few minutes to a few hours was recorded during this period, with the strongest bursts on the 9th and 10th.

"Incandescence from Crater 2 was again noted 17-26 September with an increase of audible explosions and rumblings. During this period there were several ashfalls at the observation post and Kilenge Mission. Ash was also reported at Siassi, Umboi Island (30 km W) on 24 and 25 September. The brightest glow and highest level of tremor during this period were on 23 and 24 September."

Information Contacts: J. Mori, RVO.

October 1985 (SEAN 10:10) Cite this Report

Increased activity; ash plumes

"The eruption of Crater 2 persisted through October with periods of increased activity from 4-7 and 14-25 October. When inspected on 2 and 3 October, the 200-m-wide crater was only 50 m deep, plugged with a magma column covered by debris. High-pressure degassing was occurring from six fissures in the crater floor. Occasional explosions that may have been phreatomagmatic produced ash-laden plumes.

"Intensification of magmatic activity on the 4th resulted in sub-continuous Strombolian ejections to 250 m above the crater and intermittent Vulcanian explosions. A light to dark grey ash-laden plume rose 1500 m above the crater, and produced ashfall 10 km downwind. Loud rumbling noises and sharp explosions were heard at an observation post 9 km N of the volcano. Periods of seismic tremor lasting from a few minutes to a few hours were recorded during this time.

"Activity returned to the former degassing mode 7-18 October, but eruptions resumed after the 19th. The strongest seismic activity was recorded on the 19th and 20th but harmonic tremor lasted until the 24th. Strombolian eruptions were discontinuous 19-24 October and a few Vulcanian explosions expelled dark ash-laden columns to 2000 m above the crater. By the end of the month, the eruptive activity had declined to persistent degassing, with a few explosion shocks recorded daily."

Information Contacts: P. de Saint Ours, RVO.

November 1985 (SEAN 10:11) Cite this Report

Two small explosions

"Activity was at a low level during November with occasional reports of grey ash clouds from Crater 2. A column of dark cloud was reported rising to about 200-300 m above the summit on the 30th. Two audible explosions (heard at the observation post, 10 km NW of the crater) were reported on the 17th and 30th. Crater 3 remained inactive throughout the month. Seismic activity remained at a low level throughout the month with only 2 explosion shocks recorded, on the 17th and the 30th."

Information Contacts: B. Talai, RVO.

December 1985 (SEAN 10:12) Cite this Report

Glow and explosions on 29 December

"Activity was at a low level for most of December. Starting the 29th there were daily reports of rumbling sounds and light ashfalls at the observation post 10 km NW of the summit. Glow was noted from Crater 2 on the night of the 29th. Seismic activity also increased from the 29th, with several Vulcanian explosions recorded per day and some harmonic tremor.

Information Contacts: J. Mori, RVO.

January 1986 (SEAN 11:01) Cite this Report

Explosions and tremor

"Moderate activity, which had begun in late December 1985 (10:12), continued for the first half of January. Numerous explosions from Crater 2 were seen, and there were daily reports of rumbling sounds at the observation post [9] km N of the summit. A light ashfall was reported at the observation post on 3 January. Occasional incandescence from Crater 2 was seen at night until the 13th. Low-frequency harmonic tremor was recorded on the 2nd, 3rd, and 7th. Numerous explosions (3-30/day) were recorded throughout January.

Information Contacts: P. Lowenstein, RVO.

February 1986 (SEAN 11:02) Cite this Report

Explosions and seismicity

"A moderate level of activity continued in February. Crater 2 occasionally released white to greyish vapour. A number of explosion shocks (0-10 daily) were recorded, some of which were heard at the Cape Gloucester observation post . . . . Two periods of high background seismicity, consisting of sub-continuous, high-frequency 'tremor,' occurred 6-11 and 21-25 February, possibly related to periods of high rainfall. Weak, fluctuating glow was observed on the night of the 20th."

Information Contacts: P. Lowenstein, RVO.

March 1986 (SEAN 11:03) Cite this Report

Ash emission and glow; explosion earthquakes

"Activity at Crater 2 in March was slightly higher than in February. Moderate to strong white to grey emissions were released intermittently throughout the month. Light ashfalls were reported [9] km downwind on 4 and 14 March. Weak night glows (with intermittent incandescent ejections) were reported on 16, 24, and 23 March. Explosion and rumbling noises were heard on the 4th, 9th, 14-16th, 18th, and 24-30th. Seismicity was at a moderate level with 2-10 Vulcanian explosion events/day."

Information Contacts: P. Lowenstein, RVO.

April 1986 (SEAN 11:04) Cite this Report

Ash and incandescent tephra ejected

"A further increase in activity at Crater 2 occurred in April. Weak to strong emissions of white to grey plumes were observed on most days and fine ashfalls occurred [9] km downwind on 2 and 27 April. Weak to moderate explosions and rumblings were heard on most days. Weak red crater glow was seen on ~30% of the nights and ejections of incandescent lava fragments were occasionally observed. Vulcanian explosions were recorded at rates of 0-3/day, but other higher frequency events and periods of harmonic tremor were also recorded."

Information Contacts: P. Lowenstein, RVO.

May 1986 (SEAN 11:05) Cite this Report

Explosions and glow

"Crater 2 remained moderately active in May. White to grey emissions were reported daily with light ashfalls at the Cape Gloucester airstrip . . . on 11 days. Weak rumbling noises were reported on most days with occasional explosion sounds.

"Incandescence at the summit was reported 5-8 and 11 May. The brightest glow was on the night of 7 May. During this period of increased activity, explosion sounds were heard more frequently and 10-15 explosion shocks/day were recorded on the seismograph.

"During the last 5 days of May, activity decreased; emissions were weaker and no audible noises were produced by the volcano. There was no low-frequency tremor recorded during the month."

Information Contacts: P. Lowenstein, RVO.

June 1986 (SEAN 11:06) Cite this Report

Occasional explosions; light ashfalls

"Activity in June remained at the low level established in late May. Explosion sounds were heard on only two days (11th and 20th) and no sightings of crater incandescence were made. Emissions from Crater 2 were usually white vapours at low rates, but grey or brown ash emissions were noted on 11 days in the month. Fine ashfalls took place at the Cape Gloucester airstrip . . . on two days. Seismicity was at a very low level with only a few volcanic earthquakes recorded during the month."

Information Contacts: C. McKee, RVO.

July 1986 (SEAN 11:07) Cite this Report

Weak seismicity and vapor emission

"Activity was very low in July. Emissions were limited to weak white vapours. There were no reports of incandescence or audible sounds from the summit, and seismicity was at a very low level."

Information Contacts: J. Mori and C. McKee, RVO.

August 1986 (SEAN 11:08) Cite this Report

Weak vapor emission

"Activity was very low in August. Emissions were limited to weak white vapours. There were no reports of incandescence or sounds from the summit, and seismicity was at a very low level."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

October 1986 (SEAN 11:10) Cite this Report

Low-level seismicity; weak vapor emissions

"Langila remained at non-eruptive levels of activity with emissions restricted to weak white vapour. There were no reports of incandescence or audible sounds from the summits, and seismicity was at a very low level."

Information Contacts: P. Lowenstein and P. de Saint-Ours, RVO.

November 1986 (SEAN 11:11) Cite this Report

Ash emission; low levels of seismicity

"Steam and occasional grey-brown, low-density ash clouds were emitted throughout November. Light, fine ash fell [9] km N of the vent on 14 and 22 November. Seismicity was at a very low level."

Information Contacts: B. Talai and P. Lowenstein.

December 1986 (SEAN 11:12) Cite this Report

Light ashfall; weak seismicity

Weak to moderate amounts of white vapor issued from Crater 2 during December, but no sounds or summit incandescence were reported. Small quantities of ash fell at the observation post . . . on 15 December. A pilot described a black plume rising to 1,500 m on 3 January but the report could not be confirmed by the local observer. Seismic activity remained at a low level.

Information Contacts: J. Mori and P. Lowenstein, RVO.

January 1987 (SEAN 12:01) Cite this Report

Weak vapor emission; low seismicity

Activity remained at a low level in January. Weak to moderate white to occasionally grey [emissions] from Crater 2 were observed. There were no reports of audible sounds or incandescence from the summit. Seismic activity remained at a low level.

Information Contacts: J. Mori and P. Lowenstein, RVO.

February 1987 (SEAN 12:02) Cite this Report

Weak steam emission

"Crater 2 continued weak release of white to pale grey emissions. Crater 3 activity was limited to weak fumarolic emissions."

Information Contacts: P. Lowenstein, RVO.

March 1987 (SEAN 12:03) Cite this Report

Occasional ash emission

Activity continued at a low level during March. Crater 2 emitted mostly weak white vapour with occasional ash clouds. There were no reports of sound effects or incandescence from the summit. Seismicity remained at a low level.

Information Contacts: B. Talai and P. Lowenstein, RVO.

April 1987 (SEAN 12:04) Cite this Report

Ash cloud to 3 km height

Activity was generally at a low level in April with weak white vapour emission from Crater 2 and little or no activity at Crater 3. However, a strong explosion occurred at Crater 2 on 12 April, propelling an ash cloud to ~3 km above the volcano. The explosion was heard [9] km away where fine ashfall was noted. Preliminary examination of the ash indicated that it contained little or no fresh material.

Information Contacts: C. McKee and P. Lowenstein, RVO.

October 1987 (SEAN 12:10) Cite this Report

Single ash emission

Activity . . . continued at a low level in October except for a single explosion on the 9th, which produced a dark brown ash column ~300 m high. Weak-moderate white vapour was emitted continually from Crater 2 during the month, while Crater 3 was quiet.

Information Contacts: J. Mori, D. Lolok, and P. Lowenstein, RVO.

November 1987 (SEAN 12:11) Cite this Report

Weak summit glow; rumbling; minor ash emissions

A moderate increase in activity began the second week of November; a weak glow from Crater 2 was noted, accompanied by low rumbling noises and a weak-moderate white-gray plume. Seismicity showed no significant change and there was no activity from Crater 3.

Information Contacts: P. Lowenstein, RVO.

December 1987 (SEAN 12:12) Cite this Report

Pale gray plumes; summit glow

Activity continued at a low level in December. Weak to moderate, pale grey emissions from Crater 2 were noted occasionally throughout the month, and weak rumbling, roaring, and explosion noises were heard on a few days during the first half of December. Weak glow from this crater was seen on two days at mid-month.

Information Contacts: C. McKee and P. Lowenstein, RVO.

January 1988 (SEAN 13:01) Cite this Report

Ash column; seismicity

Low-level emissions and seismicity continued during January. Crater 2 emitted small amounts of white vapor for most of the month. Weak glow from Crater 2 was observed at night 17-22 January. For several hours on the morning of 23 January it produced a dark gray ash column.

Information Contacts: J. Mori and P. Lowenstein, RVO.

February 1988 (SEAN 13:02) Cite this Report

Explosion sounds; glow; minor seismicity

Low-level activity continued during February. Emissions consisted of weak white vapors from Crater 2 for most of the month. Weak explosion sounds were heard on 8 and 21 February, then more frequently between the 25th and 27th. Weak, deep, roaring noises were heard starting on the 13th and a weak night glow was observed 27-28 February. Crater 3 was inactive. Microseismicity remained at a very low, non-eruptive level.

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

March 1988 (SEAN 13:03) Cite this Report

Small ash explosions; incandescent tephra

Eruptive activity was at a low level throughout March. Background activity consisted of release of small volumes of white vapour from Crater 2, with occasional deep, low rumbling noises. Weak to loud explosion sounds were heard at 1- to 8-day intervals. The largest explosions (on 4, 11, 12, 14, and 17 March) ejected ash-laden clouds to 300-600 m above the crater, causing light ashfalls on coastal villages. The main explosions (Vulcanian or phreatomagmatic) were followed by a period of incandescent, Strombolian-like projections to ~60 m above the crater rim and a bright to dull crater glow that persisted for a few hours. Crater 3 was inactive except for weak greyish vapour emission 2-4 March. Microseismicity remained at a low level, although the major explosions were recorded.

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

April 1988 (SEAN 13:04) Cite this Report

Small explosion ejects incandescent lava

"Activity continued at a low level throughout the month. Crater 2 occasionally emitted weak to moderate white vapours. Occasional deep, low, rumbling noises were heard throughout the month, and one deep explosion on 3 April was accompanied by a weak ejection of incandescent lava fragments. Crater 3 continued to be relatively inactive, with only weak vapour emissions on 16, 28, and 29 April. Seismicity remained at a low level with occasional Vulcanian explosion events recorded."

Information Contacts: D. Lolok, C. McKee, and B. Talai, RVO.

May 1988 (SEAN 13:05) Cite this Report

Occasional weak glow; Vulcanian explosion events

"Activity remained at a low level during May. Crater 2 occasionally produced weak to moderate white-grey emissions. Low rumbling noises were heard on the 19th, 20th, and 24th-26th. Weak glows from this crater were seen on 4, 18, 19, and 22 May. Crater 3 remained virtually inactive, with only weak white vapour emissions on the 21st and 24th. Seismicity remained at a low level with occasional Vulcanian explosion events recorded."

Information Contacts: H. Patia and P. Lowenstein, RVO.

June 1988 (SEAN 13:06) Cite this Report

Weak-moderate gas emission; glow

"Activity remained at a low level during June. Crater 2 occasionally produced weak to moderate white-grey emissions. Low rumbling noises were heard on 4, 12, 15, 19, and 27 June. Weak night glow was seen above this crater 14-19 June. Crater 3 remained virtually inactive with only weak white vapour emissions on 17 June."

Information Contacts: P. de Saint-Ours and P. Lowenstein, RVO.

July 1988 (SEAN 13:07) Cite this Report

Ash emission and glow

"A generally low level of activity continued during the first half of July. Crater 2 produced occasional weak emissions of pale-grey ash and vapour, sometimes accompanied by weak explosions. From about 19 July, more sustained explosive activity occurred. Light ashfalls were reported ~10 km from the crater on 20 and 21 July. Weak red glow from the crater was seen on the night of the 21st. Only a few explosions were large enough to be recorded at the seismic station . . . ."

Information Contacts: C. McKee and P. Lowenstein, RVO.

August 1988 (SEAN 13:08) Cite this Report

Vapor emission, faint glow

"Crater 2 continued to release white with occasional grey [emissions] at low rates. Deep low rumbling sounds were heard on 1, 6, 13, and 24 August and weak red glow was observed on the 5th, 18th, and 22nd."

Information Contacts: P. Lowenstein and B. Talai, RVO.

September 1988 (SEAN 13:09) Cite this Report

Weak ash emission; glow

"Low-level activity continued in September. Weak-moderate white emissions and occasional grey ash clouds were released from Crater 2. Explosion and rumbling sounds were heard on a number of days and weak crater glow was observed on the nights of the 5th and 14th. No eruptive activity took place at Crater 3. Seismic activity was low and only a few explosion earthquakes were recorded during the month."

Information Contacts: C. McKee and P. Lowenstein, RVO.

October 1988 (SEAN 13:10) Cite this Report

Two Vulcanian explosions; glow

"Activity increased slightly in October. Weak to moderate white with occasional grey emission continued from Crater 2 throughout the month. Steady weak glow was observed for about a week (5-11 October) at Crater 2. Two loud Vulcanian explosions occurred on the 27th and 30th. Crater 3 remained relatively inactive with only weak white and grey emissions on 1, 5, 8, 9, and 17 October."

Information Contacts: D. Lolok, B. Talai, and P. Lowenstein, RVO.

November 1988 (SEAN 13:11) Cite this Report

Activity subsides to occasional ash emission

"Activity returned to a low level in November. Weak-moderate amounts of white vapour with occasional grey [ash] were emitted from Crater 2. Weak rumbling noises occasionally were heard on the 4th. Ashfall was observed on the 11th. Two Vulcanian explosions, on the 18th and 27th, were accompanied by ash columns that rose a few hundred meters. Crater 3 was inactive throughout the month. Seismicity remained low and only 9 explosion earthquakes were recorded."

Information Contacts: I. Itikarai and P. Lowenstein, RVO.

December 1988 (SEAN 13:12) Cite this Report

Small Vulcanian explosion

"Low-level activity continued in December. Weak to moderate white emissions with occasional grey ash clouds were released from Crater 2. Weak rumbling noises were heard 28-31 December. A Vulcanian explosion on the 4th ejected an ash column that rose a few hundred metres and resulted in light ashfall to the SE. Crater 3 remained inactive throughout the month. Seismic activity remained at a low level with <10 events/day near the end of the month."

Information Contacts: H. Patia and P. Lowenstein, RVO.

January 1989 (SEAN 14:01) Cite this Report

Ash emission; glow; explosion seismicity

"Activity increased slightly on 26 December and continued into January. A number of low-frequency explosion earthquakes (2-9) were recorded daily, some of which were accompanied by loud detonations heard at the the observation post . . . . Weak to loud rumbling noises were often heard and moderate pale-grey ash and vapour clouds were released from Crater 2. Weak red glow was observed at the summit on the nights of 4 and 9-11 January, by which time the number of explosion shocks had decreased to 1-3/day. One louder Vulcanian explosion took place on the 11th, producing a thick dark ash column. Weak red glow was observed again on the nights of 15-16 January and occasional weak rumbling noises were heard until the 21st. Occasional weak vapour emissions were observed from Crater 3 on the 4-5th, 10-11th, 13th, and 22nd."

Information Contacts: C. McKee, H. Patia, and P. de Saint-Ours, RVO.

February 1989 (SEAN 14:02) Cite this Report

Vapor and ash emission; detonations; weak glow

"Activity declined somewhat in February following the slight increase in late December-mid January. Weak-moderate emissions of white to pale-grey vapour and ash clouds were released from Crater 2 during most days of the month. Occasional weak rumbling noises were heard from Crater 2, and detonations were heard on the 14th and 22nd. Weak red glow from this crater was seen 6, 8, 9, 23, and 24 January. Crater 3 remained inactive throughout the month."

Information Contacts: D. Lolok and C. McKee, RVO.

March 1989 (SEAN 14:03) Cite this Report

Occasional explosion earthquakes and glow

"There was a slight increase in March in the overall low level of inter-eruptive activity since the last significant eruption in March-May 1986 (SEAN 11:3-5). During the first week of March, 2-7 low-frequency explosion earthquakes were recorded daily, some of which were accompanied by detonations heard at the observation post . . . . Weak rumbling noises were occasionally heard and weak red glow was reported on the nights of 28 and 29 March. Vapour emission from Crater 2 was of moderate volume throughout the month with occasional grey ash clouds. Crater 3 was inactive."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

April 1989 (SEAN 14:04) Cite this Report

Moderate ash ejections and glow

"The slightly stronger activity from Crater 2 reported in March continued in April, although fluctuations in the level of activity were evident. The volcano was quiet at the beginning of the month. Between 5 and 23 April, moderate ash emissions were observed, accompanied by weak to strong rumbling sounds. Most ash fell near the volcano. On most nights during this period, weak red glow was observed above Crater 2. Activity subsided between 24 and 28 April, but on the 29th and 30th returned to the levels seen at mid-month. Seismic records were unavailable between 14 and 30 April. During the first half of the month, seismicity was at a low level with only 0-1 explosion earthquakes/day."

Information Contacts: C. McKee, RVO.

May 1989 (SEAN 14:05) Cite this Report

Ash emission and glow

"The slightly stronger activity . . . continued through May. Moderate grey emissions were released from Crater 2 throughout the month, accompanied by occasional weak rumbling noises. One loud explosion was heard on the 30th. Weak red glows from this crater were seen 23, 29, and 30 May, and incandescent lava fragments were ejected above the summit on the 30th. Occasional, thin, white-grey emissions were observed from Crater 3 on 1-4, 7-8, 16, 19-20, 24, and 29-31 May, more frequently than normal."

Information Contacts: H. Patia and C. McKee, RVO.

June 1989 (SEAN 14:06) Cite this Report

Activity subsides; landslides widen crater

"Langila returned to very subdued activity in June. Crater 2 released moderate white-grey emissions, accompanied by occasional rumbling noises. Explosions were heard on 1, 2, 6, 24, and 30 June, and a weak red glow was seen above this crater on the night of the 14th.

"When the volcano was inspected on 10 June, Crater 2 had enlarged and deepened since the last field inspection in October 1985 (10:10). The flat, [40]-m-wide, annular platform that formerly surrounded the crater had caved in, resulting in an estimated [130]-m wide crater with a narrow ledge. The crater now has a composite funnel shape produced by the sinking of the former magma plug in two successive steps. The top of the active plug (responsible for the occasional night glow) is now at ~1,045 m altitude (the crater rim is at 1,100-1,120 m) and clogged by debris from sub-continuous rocksliding.

"Crater 3 . . . remains inactive. The crater is sealed at ~900 m asl by a flat muddy floor from wash-outs of the walls (the crater rim is at 1,045-1,080 m altitude). The source of white vapour occasionally observed from the observatory is an active fumarole at the base of the sub-vertical S wall."

Information Contacts: P. de Saint-Ours and B. Talai, RVO.

July 1989 (SEAN 14:07) Cite this Report

Occasional ash ejection

"A steady decrease in volcanic activity was observed at Crater 2 during July, while Crater 3 remained inactive. Emissions from Crater 2 were mostly white but occasionally grey (on 7, 16, 18, 20, 21, 26, and 27 July), and weak to moderate in volume. Occasional low rumbling sounds were heard from the 1st to the 20th and on the 28th. One loud explosion on the 16th accompanied the ejection of thick brownish-grey ash, forming a column that rose 1200 m above the crater. Night glow around the crater mouth was visible only on the 1st and 5th."

Information Contacts: B. Talai and C. McKee, RVO.

August 1989 (SEAN 14:08) Cite this Report

Activity declines to gas emission

"Activity at Crater 2 dropped to its lowest level of the year, releasing mostly weak to moderate white vapour with occasional weak to moderate grey emissions (on 18, 19, 21, and 22 August). Crater 3 remained inactive throughout August, except on the 19th, when [weak] to moderate white vapour emissions were observed."

Information Contacts: I. Itikarai and C. McKee, RVO.

September 1989 (SEAN 14:09) Cite this Report

Weak explosive activity; ashfalls

"Activity intensified somewhat during September. Weak explosive activity took place at Crater 2 on most days. The ash content of emissions was generally low, but ashfalls were recorded [~9] km downwind on the 5th and 16th. Sound effects at the observation post usually consisted of weak rumblings, but one loud explosion was heard on the 16th."

Information Contacts: C. McKee, RVO.

October 1989 (SEAN 14:10) Cite this Report

Vulcanian explosion; ash to coast; night glow

"After 2 months of very weak activity, night glow was seen over Crater 2 on the nights of 7, 17, and 20 October, and steadily from the 24th to the 26th. Weak glow on the night of 30 October was followed on the 31st by a Vulcanian explosion that resulted in light ashfall on the coast, 10 km downwind. The amount of vapour released by this crater increased throughout September and October. Low rumbling noises and occasional discrete explosion sounds were heard. There was no sign of activity from Crater 3 . . . , apart from occasional wisps of white to greyish vapour. Seismicity increased at the beginning of the month from a background of a few tens to several hundreds of moderate-amplitude B-type events/day, occasionally merging into periods of sub-continuous tremor lasting several minutes."

Information Contacts: C. McKee, RVO.

November 1989 (SEAN 14:11) Cite this Report

Moderate vapor emission; weak glow

"Activity remained at a moderate level in November. Vapour was released by Crater 2 in small to moderate amounts. Deep rumbling noises and a weak red glow were reported at the beginning (1st and 2nd) and end (29th and 30th) of the month. Crater 3 released weak [emissions of white vapour]."

Information Contacts: D. Lolok and P. de Saint-Ours, RVO.

December 1989 (SEAN 14:12) Cite this Report

Moderate seismicity; weak glow

"Although a weak red glow was observed over Crater 2 on most nights of the month, activity at Langila remained at a moderate level throughout December. Vapours were emitted in small to moderate amounts, and deep rumbling noises were occasionally heard. The seismicity consisted of a few tens to several hundreds of small-amplitude B-type events/day."

Information Contacts: P. de Saint-Ours, RVO.

January 1990 (BGVN 15:01) Cite this Report

Occasional Vulcanian explosions recorded; weak red glow; vapor emission

"Activity remained at a moderate level throughout January. Weak red glow was observed over Crater 2 on every clear night of the month. Vapour was released in weak to moderate amounts. The seismicity consisted of numerous daily B-type events of small amplitude and an occasional Vulcanian explosion shock. Crater 3 was inactive except for weak fumarolic emissions."

Information Contacts: I. Itikarai and P. de Saint-Ours, RVO.

February 1990 (BGVN 15:02) Cite this Report

Small ashfalls in uninhabited areas; weak red glow from crater

"Moderate vapour and ash emissions continued at Crater 2. Ashfalls were mainly in uninhabited areas SE of the volcano, but on one occasion there was a fine ashfall ~10 km to the NW. Weak red crater glow was often seen at night. Seismicity was generally at a low level. Vulcanian explosion earthquakes were occasionally recorded."

Information Contacts: C. McKee, RVO.

March 1990 (BGVN 15:03) Cite this Report

Glow; gas emission; rumbling

"Activity consisted of weak to moderate white-grey emissions from Crater 2. Weak, steady, red glow was observed 1-4 and 25-31 March. Rumbling noises were heard on the 28th and 29th. Crater 3 remained quiet throughout the month. Seismicity was at a low level."

Information Contacts: I. Itikarai, P. de Saint-Ours, and C. McKee, RVO.

April 1990 (BGVN 15:04) Cite this Report

Vapor emission; glow; rumbling

"Activity was limited to weak or moderate emissions of white vapour from Crater 2, with a weak, steady, red glow at night from 25 March until 6 April, and 9-11 and 27-28 April. Occasional weak, deep rumbling noises were heard on 3 consecutive days 12-14 April. Crater 3 remained inactive, apart from thin white vapour released by fumaroles in the crater."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

May 1990 (BGVN 15:05) Cite this Report

Vapor emission, glow, periodic explosions

"A low level of activity prevailed at Langila. Crater 2 released white vapour in moderate amount during the first half of the month, when a steady night glow could be seen (until the 17th). From the 20th onward, 1-3 explosion earthquakes were recorded daily while background seismicity remained at a low level. The amount of vapour released by Crater 2 decreased in the last week of May. Crater 3 remained inactive, apart from thin white vapour released by fumaroles in the crater."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

June 1990 (BGVN 15:06) Cite this Report

Vulcanian explosion earthquakes; weak red glow

"A low level of activity prevailed . . . although there was an increase toward the end of the month. Crater 2 released a weak to moderate vapour and ash cloud while Crater 3 remained virtually inactive. Vulcanian explosion earthquakes were recorded occasionally. A weak red glow was observed over Crater 2 on most nights after 23 June."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

July 1990 (BGVN 15:07) Cite this Report

Ash emission and glow

"An increase in activity at Crater 3, which had been inactive since April 1983, began towards the end of June and continued during July. The increased activity was characterized by emission of white, grey, and brown vapour and ash clouds with occasional blue vapour. Explosion earthquakes were recorded on most days with daily totals ranging from 0 to 14 events. They were often accompanied by tremor lasting 1-10 minutes and the rise of Vulcanian ash clouds over the crater. Ashfalls were reported in areas N and NW of the volcano. Occasional deep rumbling noises were heard after the 8th. A weak glow was seen on 16-18, 24, and 31 July.

"Crater 2 released white, grey and occasional blue emissions. Steady night glow was seen throughout the month without any other sign of eruptive activity."

Information Contacts: H. Patia and C. McKee, RVO.

August 1990 (BGVN 15:08) Cite this Report

Continued moderate Vulcanian activity

"Moderate Vulcanian activity involving Crater 3 continued. Crater 3 . . . was releasing a plume of white vapour with frequent ash-laden clouds accompanied by weak Vulcanian explosions. The largest of these explosions (recorded by the nearby seismometer) totaled as many as 35/day. Ashfalls were reported in areas N and NW of the volcano. Rumbling noises were heard on 7 August and glows were observed on the 13th and 18th, associated with weak explosions.

"Meanwhile, emissions from Crater 2 consisted of white with occasionally blue vapour. Steady weak night glows were occasionally observed."

Information Contacts: I. Itikarai and C. McKee, RVO.

September 1990 (BGVN 15:09) Cite this Report

Continued Vulcanian activity

"Moderate Vulcanian activity involving Crater 3 continued in September. Crater 3 produced frequent mild Vulcanian explosions, with occasional larger ones (6-38/day). The larger explosions, which ejected clouds to as much as 500 m above the crater, generated large-amplitude, impulsive seismic signals, while many of the smaller explosions were almost aseismic. A small pyroclastic avalanche may have been produced on 2 September. Incandescent rocks were observed tumbling down the NW flank at about 0330, accompanied by loud explosions and rumbling sounds. Ashfalls were reported from inhabited areas ([~9] km downwind) on six days. Ejections of incandescent lava fragments were reported 3-5 September, and steady crater glow was observed on 10 September.

"Activity at Crater 2 consisted mainly of weak-moderate emissions of white vapour, with rare ash emissions. The emissions sustained a column 100-200 m high and a plume several kilometers long. Deep rumbling sounds were heard on many days, and weak crater glow was frequently observed.

"An aerial inspection on 3 September revealed that Crater 3 is ~100 m in diameter and its N rim is markedly lower than the S rim. The active vent is in the N part of the crater and has built a small cone of ejecta. Crater 2 is ~150 m across and has a shallow bowl shape. The active vent has formed a funnel-shaped crater in the NE part of Crater 2."

Information Contacts: I. Itikarai and C. McKee, RVO.

October 1990 (BGVN 15:10) Cite this Report

Occasional ash emission; explosion sounds; glow

"Activity returned to a low level in October . . . . Emissions from Crater 3 consisted mainly of occasional weak to moderate, white and grey, ash and vapour clouds. Deep, low, explosion and rumbling noises were heard on 6 and 7 October, respectively. Weak steady glow was observed on the 6th and the 9th. Activity at Crater 3 was somewhat subdued during the last week of October. Crater 2 released weak and occasionally moderate white and at times blue vapour throughout the month. Deep weak rumbling noises were heard between 16 and 28 October and steady weak glow was seen throughout the month."

Information Contacts: C. McKee and I. Itikarai, RVO.

November 1990 (BGVN 15:11) Cite this Report

Ash emission and glow

"Activity remained at a low level in November . . . . Crater 3 emitted mainly weak to moderate white-grey ash and vapour clouds. However, stronger emissions on 12 and 25 November produced eruption columns ~200 m high and ashfalls ~10 km downwind. Weak deep explosions from Crater 3 were heard on 28 and 29 November. Emissions from Crater 2 consisted mainly of weak to moderate white and grey vapour and ash, and rarely, blue vapour. Steady weak glow was observed throughout the month. The only sound from this crater during November was a deep loud explosion on 28 November and rumbling noises on the 29th and 30th. Seismic activity was at a moderate level."

Information Contacts: C. McKee and I. Itikarai, RVO.

December 1990 (BGVN 15:12) Cite this Report

Weak ash emission and glow; seismicity declines

"Activity was at a moderate-low level in December. Crater 2 occasionally emitted weak-to-moderate white and grey vapour and ash clouds. Weak rumbling from Crater 2 was heard 12 December. Steady weak red glow from this crater was observed at night on 7, 8, 12-17, 28, and 31 December. Activity at Crater 3 was similar to that at Crater 2. Night glow from the crater was seen once, on 7 December.

"Seismic activity was at a moderate level during the first half of the month (up to ~30 explosion earthquakes/day), but declined to a low level at mid-month. During the second half of the month, daily totals of volcanic earthquakes were in the range 0-4."

Information Contacts: B. Talai, RVO.

January 1991 (BGVN 16:01) Cite this Report

Ash emission and weak glow

"Activity was steady at a low level throughout January, as it has been since mid-October 1990, and was essentially limited to Crater 2. Even though that crater maintained a weak red glow at night, emissions were limited to small volumes of white-greyish vapour and ash. Emissions from Crater 3 were very weak. Only one explosion earthquake was recorded during 11 days of seismic monitoring."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

February 1991 (BGVN 16:02) Cite this Report

Vapor/ash emission and glow

"Activity remained at a low level in February. Crater 2 continued to produce weak-moderate emissions of white to pale grey vapour and ash, and at night a steady weak red glow was observed over the crater. Crater 3 emissions consisted of white vapour released at very low rates. Seismicity was also at a low level. On most days there were no volcanic earthquakes, but between 6 and 16 February up to 4 events/day were recorded."

Information Contacts: C. McKee, RVO.

March 1991 (BGVN 16:03) Cite this Report

Explosions and ash emissions; night glow

"A slight increase in activity was evident towards the end of March. Explosions from Crater 2 were more common from the 24th, producing grey ash and blue vapour emissions. Light ashfalls were observed on the NW slopes of the volcano. Steady weak red glow from this crater was observed most nights. Seismicity was very weak for most of March, but from the 24th onwards, 2-8 explosion events/day were recorded."

Information Contacts: C. McKee, RVO.

April 1991 (BGVN 16:04) Cite this Report

Ash emission and glow

"Activity declined in early April . . . . Emissions from Crater 2 consisted of moderate to weak white-grey ash and vapour. An explosion on 3 April produced a dark ash column that rose ~500 m above the crater and resulted in ashfall on the NW side of the volcano. Steady weak red glow from the crater was observed on most nights. Following the first few days of stronger seismicity, when up to four explosion earthquakes/day were recorded, the seismicity declined and on most days no explosion events were recorded."

Information Contacts: C. McKee, RVO.

May 1991 (BGVN 16:05) Cite this Report

Ash emission resumes; steady glow

"After 7 months of quiescence, Crater 3 was reactivated. Resumption of activity, which started on 16 May, was manifested by the release of moderately thick white-to-grey vapour clouds with occasional blue vapours, and the recording of explosion earthquakes (2-20/day). After 18 May, deep rumbling noises and/or loud Vulcanian explosions were heard at the Cape Gloucester observation post . . . and light ashfalls occurred on the NW flank of the volcano. A weak steady red glow was observed over this crater at the end of the month.

"Activity at Crater 2 . . . did not seem to be affected. This crater kept on releasing moderate to weak emissions of white vapour and displayed a steady weak night glow."

Information Contacts: D. Lolok and P. de Saint-Ours, RVO.

June 1991 (BGVN 16:06) Cite this Report

Frequent Vulcanian explosions

"Crater 3 . . . produced 1 to >40 Vulcanian explosions/day in June. The explosions produced dark grey vapour and ash clouds or columns, resulting in light ashfalls over the NW flank of the volcano and to coastal villages (10-15 km distant). Villagers were also shaken by the airwaves of the strongest explosions. Night activity consisted of weak red glow, with the largest explosions producing a short-term brighter glow between 5 and 16 June.

"Crater 2 released weak to moderate white vapour emissions plus occasional grey ash and blue vapours. The crater produced one loud Vulcanian explosion on 28 June, accompanied by an ashfall. A steady weak night glow was visible over the crater for much the same period as at Crater 3 (3-17 June). After a 10-day absence, night glow reappeared at Crater 2 on 28 June, following its throat-clearing Vulcanian explosion. Two days later, night glow also returned to Crater 3.

"The daily number of Vulcanian explosions from Crater 3 reached its maximum level of >30 between the 15th and 19th, coinciding with the absence of night glow at both craters (figure 3). A seismograph 9 km away (CGA), which previously recorded ~10% of the explosion earthquakes detected by the summit station (LAN), started to record an increasing proportion of these events (to >50%)."

Figure 3. Number of explosion earthquakes/day recorded at Langila's summit seismic station (LAN) and a second station (CGA) 9 km away, late May-early July 1991. Periods of glow at craters 2 and 3 are shown by shaded areas along the bars at bottom. Courtesy of RVO.

Information Contacts: P. de Saint-Ours, RVO.

July 1991 (BGVN 16:07) Cite this Report

Tephra emission and seismicity

"Activity of both craters remained moderately strong in July, as in June. Crater 3, which had resumed activity in mid-May, released white-to-grey vapor and ash clouds, and light ashfall occurred towards the NE of the volcano on the 6th and 8th. Occasional weak to loud explosions were heard throughout the month. Weak to bright red glow was observed on the 8th, 9th, 13th, and throughout the last week of the month.

"Activity at Crater 2 was characterized by the emission of moderate to thick pale grey ash clouds. Occasional loud to low explosions, some of which were accompanied by light ashfall, were heard during the second and last week of the month. Steady, weak night glow was visible throughout the second week and on the 22nd and 23rd.

"Seismicity remained high throughout the month, with the occurrence of explosion earthquakes and tremor. The daily number of Vulcanian explosions recorded by the summit station (LAN) reached a maximum of 40-60 between the 21st and 26th. Tremor, hardly noticeable in May, occurred almost daily in June-July (up to 100-200 minutes/day). Two types were recognized: high-frequency, discontinuous tremor periods, lasting 1-2 minutes; and lower-frequency harmonic tremor, continuous for periods of several (up to 10) minutes. The tremor became strong enough to be recorded at both the summit station (LAN) and the 9-km-distant CGA station."

Information Contacts: C. McKee, RVO.

August 1991 (BGVN 16:08) Cite this Report

Ash clouds; incandescent tephra; lava flows in crater

"In August, Crater 3 frequently erupted moderate to strong, pale grey-brown ash and vapour clouds accompanied by weak to loud detonations, roaring or rumbling. The eruptions occurred at intervals of several minutes to a few hours. The emission clouds rose as much as 500 m above the crater. Dull to bright red crater glow was observed on the nights of 7-9, 12, and 13 August.

"During an aerial inspection on the 14th, two active vents were observed in a mound of lava filling Crater 3. The vents were ~5-10 m in diameter, 40 m apart and aligned approximately N-S. The N vent was more active and was filled with incandescent lava. The S vent was clogged with dark lava. Both vents released blue vapour. Lava had flowed eastward to form a short (70 m) lobe in the E part of the crater. A longer (~150 m) lobe of lava was present on the NE flank of Cone 3. This lobe was fresh, having a dark surface, and its source appeared to be a tube within the E lobe. The NE-flank flow was first observed on 13 August, and appeared to be inactive then. However, some activity of this flow had been evident the previous night when prolonged incandescence in this area and some movement of incandescent material were observed. Two other very small lava lobes (both inactive) were observed on the NW flank of Cone 3.

"Throughout the month, Crater 2 (roughly 200 m E of Crater 3) almost continuously emitted moderate amounts of pale grey-brown ash and vapour. This activity was accompanied by nearly continuous low roaring sounds. Occasional stronger explosions took place. Dull glow over the crater was observed on the nights of 7-9, 13, 22, 24, and 27 August. A 30-minute period of strong explosive activity on the night of 13 August resulted in a large volume of incandescent lava fragments being ejected onto the NE flank of Cone 2. Incandescent lava-fragment ejections from Crater 2 were also seen on the night of 20 August. A brief aerial view of the interior of Crater 2 on 14 August indicated that it remains funnel-shaped, with several benches. Detailed observation was prevented, however, by emissions of ash and vapour.

"The ash plume from the combined emissions of the craters was usually directed in a sector between NNE and NW. Fine ashfalls were recorded in coastal areas (9 km distant) on 1, 2, 6, and 12 August.

"Seismicity remained at a moderate to high level throughout the month. It appeared that most of the stronger seismicity was associated with events at Crater 3. The daily number of explosion earthquakes recorded by the summit station fluctuated between 20 and 70, with the largest totals of 40-70 events on 16, 25, and 30-31 August. Meanwhile, the remote station (9 km distant) recorded 0-29 events/day. Numerous low-amplitude, short-duration, tremor-like signals were produced by weaker explosions. Several periods of harmonic tremor were recorded but the source was not determined."

Information Contacts: B. Talai, C. McKee, and P. de Saint-Ours, RVO.

September 1991 (BGVN 16:09) Cite this Report

Frequent tephra emission; tremor declines

"Moderate to strong activity persisted at Langila throughout September. Ash-laden vapor emissions were released almost continuously from Crater 2, accompanied by weak to loud rumbling sounds. A weak glow was visible on most nights, except 21-25 September. Activity at Crater 3 consisted of occasional Vulcanian explosions, at rates of 30-80/day. The activity was stronger 23-26 September and a steady night glow was visible 25-26 September.

"The amplitude of discontinuous tremor declined markedly in late August, while cumulative daily tremor duration dropped to <=100 minutes from levels that had been as high as 200 minutes/day since mid-June."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

October 1991 (BGVN 16:10) Cite this Report

Explosive activity from two craters; small pyroclastic flows

"Moderate to strong activity persisted throughout October. Crater 2 activity consisted of continuous release of white vapour, producing a small emission column that frequently (5-15 times/hour) turned into a forceful jet of ash-laden vapour, generating a whooshing sound. Occasionally, a discontinuous tremor-like signal was recorded by the 1-km-distant LAN seismometer. Light ashfalls were experienced in coastal areas 10 km downwind. On most nights this Vulcanian activity was accompanied by dull glow above the crater, becoming brighter at times when incandescent lava fragments were ejected onto the flanks of the cone.

"Activity at Crater 3 was intermittent, with periods of 5-15 minutes devoid of any emission separated by sudden forceful explosive emissions of thick, mushrooming, dark grey ash clouds that rose 400-650 m above the crater rim. The crater was more strongly active 4-10 October, when small pyroclastic flows were generated at the base of the strongest explosions, but these did not advance beyond the cone's upper flanks. Intermittent glow from the crater was accompanied by incandescent projections to ~100 m above the crater rim. Crater 3 explosions were recorded as distinct impulsive signals (5-50/day) by the LAN seismic station, with the strongest ones (1-12/day) recorded 9 km away (CGA station).

"Seismic activity dropped significantly in October. The intermittent tremor recorded since June disappeared in September but reappeared sporadically in October. Most of the seismicity consisted of discrete earthquakes. The daily totals of these events ranged from 15 to 60.

"Aerial and ground inspections were carried out 10-11 October. The main change noted since the last inspection, in mid-August, concerned Crater 3. Of the 2 active vents previously observed in the mound of lava filling the original crater, the N one (which seemed the most active in August) was inactive, while a 50-m explosion crater had formed around the S vent, which was the source of the reported Vulcanian activity. This new crater was bowl-shaped, ~6 m deep, and filled with loose debris-blocks and ash. Similar debris also extended in short tongues to <100 m outside the crater rim and probably was deposited by small pyroclastic flows such as those reported earlier in October. Within the crater were irregular arcuate ridges of loose debris that may have been deposited by pyroclastic flows. The active vent area was only ~5 m across. Although it remained glowing for a short time after each explosion, the maximum temperature measured with an infrared thermometer from 30 m distance was only 500°C when erupting, and 270°C when quiet. The temperature of the crater floor was 140-170°C.

"The short lava flow observed 12 August on the cone's N flank had cooled, but a few rootless fumaroles remained on its surface, which was partly buried under airfall blocks and ash. The flow had the rugged surface features of aa lava and was ~300 m long, extending from the crater rim (~1,100 m elev) to 950 m elev. Its thickness decreased from 2.5 m (where it spilled over the crater rim) to <1 m at its front. The volume of the flow is estimated to be <=15,000 m³.

"Crater 2 was estimated to be 130 m wide and 30 m deep. Its floor is now at the level of the upper bench described in the last ground inspection, in June 1989 (SEAN 14:06). Several small vents (<=1 m in diameter), although closely grouped at the base of the crater, were activated independently. At the times of the strongest emissions however, up to four vents erupted concurrently with a deafening jet engine noise, generating air and ground vibrations recorded by the summit seismic station as emergent periods of tremor-like signals. The westernmost vent was directing its jet of ash-laden vapour at an angle of 15° toward the SE, resulting in the backfall of blocks and spatter-like scoriae on the SE crater rim and beyond. The maximum measured temperature at the base of the jet (although glowing at times) was only 240°C, and 70°C higher up in the plume."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

November 1991 (BGVN 16:11) Cite this Report

Ash clouds; incandescent tephra

"Activity at Crater 2 remained moderately strong, while a slight decline was evident at Crater 3. Crater 2 activity consisted of continuous emission of pale ash clouds accompanied by occasional low rumbling noises. From 17 November onward, activity increased with occasional forceful eruptions of grey ash clouds, rising several kilometres above the crater, accompanied by loud or deep rumbling and explosion noises. Light ashfalls were recorded on 17, 25, and 28 November in coastal areas 10 km downwind . . . . Steady weak night glow was visible over the crater during the first half of the month, and ejections of glowing lava fragments to ~100 m above the crater rim were observed 17-26 November.

"Crater 3 activity was characterized by gentle pale-grey and blue emissions, and occasional sudden explosive ejections of thick grey ash clouds. Explosion sounds were heard 1-9 and 13-14 November. No night glow was observed.

"There was a further drop in Langila's seismic activity in November as a result of the decline in Crater 3 activity. The summit seismometer continued to record discontinuous tremor-like signals until 23 November. The daily totals of discrete events ranged from 1 to 28."

Information Contacts: B. Talai and C. McKee, RVO.

December 1991 (BGVN 16:12) Cite this Report

Ash emission and glow

"A decline in activity persisted throughout December. Crater 2 activity consisted of continuous emissions of white to grey (with occasional blue) vapours, accompanied by deep loud-to-low rumbling and explosion noises. Steady weak red glows were visible over the crater mouth during most nights. Crater 3 continued to gently and occasionally forcefully emit grey ash clouds, without any audible sounds. No night glows were observed. Despite the decline in observed surface activity, seismicity increased somewhat in December. The daily total of low-frequency events ranged from 4 to 52 . . . ."

Further Reference. Mori, J., Patia, H., McKee, C., Itikarai, I., Lowenstein, P., De Saint-Ours, P., and Talai, B., 1989, Seismicity associated with eruptive activity at Langila volcano, Papua New Guinea: JVGR, v. 38, p. 243-255.

Information Contacts: D. Lolok and B. Talai, RVO.

January 1992 (BGVN 17:01) Cite this Report

Ash ejection and glow

"Activity was at a moderate-low level in January. Crater 2 emitted white to grey ash and vapour clouds at moderate to low rates. However, on 21 January, dark ash-laden clouds rose several hundred meters above the crater rim and resulted in light ashfalls on the SE side of the volcano. Deep loud or low rumbling and explosion noises accompanying the emissions were heard throughout the month. Steady, weak red glow from this crater was observed at night on 9, 19, 24, 27-28, and 31 January. Crater 3 activity consisted mostly of emissions of weak white vapour. No noises were heard, although weak night glow was seen on 9 and 28 January around the crater rim. Seismic activity was at a low level throughout the month. Daily totals of volcanic earthquakes (all at low frequency) ranged from 0 to 16 . . . ."

Information Contacts: H. Patia, P. de Saint-Ours, and B. Talai, RVO.

February 1992 (BGVN 17:02) Cite this Report

Ash ejection and glow; increased seismicity

"During February the activity continued to be focused at Crater 2, at an intensity similar to that observed in January. However, seismicity increased in the second half of February. Emissions at Crater 2 consisted of pale-grey vapour and ash clouds in low-moderate volumes. Occasionally there were ashfalls on the lower flanks of the volcano. Explosions and rumbling sounds associated with the emissions were heard throughout the month. When the summit was free of cloud at night, a steady weak glow was seen above the crater. Activity at Crater 3 was mostly confined to weak emissions of white and blue vapours. However, there was a large explosion on 11 February that produced an emission cloud ~1 km high. Seismicity was steady at a low level in the first half of the month but then began to increase. By the end of the month seismicity had reached the level recorded in January (up to 17 low-frequency earthquakes per day)."

Information Contacts: C. McKee, RVO.

March 1992 (BGVN 17:03) Cite this Report

Incandescent tephra ejection; new lava flow

"Activity increased in March with Crater 3 becoming more active. Emissions from Crater 3 consisted of weak to moderate white-grey vapour and ash with occasional blue vapour. Weak to moderate explosion noises were frequently heard throughout the month. At night, weak to moderate red glow over the crater and occasional incandescent lava ejections were seen. A new lava flow on the cone's N flank began on 6 March and was still advancing at the end of the month. Emissions from Crater 2 consisted of low to moderate volumes of white-grey vapour and ash clouds. Thick black ash clouds were emitted towards the end of the month, resulting in ashfall on the SE side of the volcano. Rumbling and explosion noises associated with some of the emissions were heard throughout the month. Steady weak red crater glow was observed on clear nights, with incandescent lava ejections occurring on 21 and 22 March. Seismic activity was at a higher level than in January and February."

Information Contacts: I. Itikarai, P. de Saint-Ours, and C. McKee, RVO; ICAO.

April 1992 (BGVN 17:04) Cite this Report

Incandescent tephra; ash clouds; lava flows stop

"Moderate eruptive activity continued during April. Crater 2 emitted moderate volumes of pale grey ash and vapour, and occasionally there were stronger explosions that propelled ash clouds several kilometers above the summit. Ashfalls to 10 km from the source were common. Explosions were heard at the observation post . . . on most days between 1 and 11 April. Rumbling and roaring sounds were heard on 27-30 April. Steady, weak crater glow was seen on most nights. Crater 3 activity was mild at the beginning of the month, and only weak white emissions were seen. Lava flows that began 6 March ceased on 1 April. Crater 3 became more active on 6 April; however, the ash content of emissions remained low. Incandescent lava ejections and/or glow were reported on most nights beginning 6 April. The ejections rose as much as 500 m above the crater. Beginning on 9 April, the explosive activity was stronger and emissions contained more ash. Explosion noises were reportedly loud at the observation post.

"In early April, seismicity appeared to mainly reflect the activity at Crater 2, while during 7-14 April, most of the seismicity was associated with Crater-3 activity. All seismic monitoring ceased on 19 April with the failure of both seismic stations."

Information Contacts: C. McKee, RVO.

May 1992 (BGVN 17:05) Cite this Report

Moderate explosive activity from 2 craters

"Moderate eruptive activity continued during May. Crater 3 was the most steadily active. Throughout the month it produced intermittent weak and loud explosions with forceful emission of grey ash columns rising to several hundred meters above the crater. No night glow was seen until 29 May. Activity at Crater 2 was moderately strong on 1 May, with forceful dark ash clouds rising several km above the crater. After the 1 May episode, activity was relatively mild. Other than moderate volumes of white and occasionally blue vapour emission, it only produced Vulcanian explosions on 11 and 18 May.

"Both craters were reactivated on the last few days of the month. Weak incandescent projections started at Crater 3 on the night of 29-30 May. On 30 May, low to loud explosions and whooshing noises accompanied bright Strombolian ejections to 700 m above the crater. Also on 30 May, a thick, dark ash column a few km high was emitted by Crater 2, with nighttime incandescent fragments rising 125 m above the crater. On 31 May, the activity was mainly from Crater 3, with ongoing high Strombolian projections, emission of a thick grey ash column several km high, and the production of a new, short lava flow down the NW flank of the cone. Unfortunately, failure of both seismic stations prevented recording of any related seismicity. The recurring activity from both craters continued into early June, producing much ashfall on the downwind coastal areas."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

June 1992 (BGVN 17:06) Cite this Report

Strombolian explosions and lava flow

"A new phase of eruptive activity that started on 30 May lasted until 8 June. From 1 to 4 June, both Crater 2 and Crater 3 produced ash-rich Strombolian explosions to 500-700 m height. A new, short lava flow was emplaced on the NW flank of Crater 3. Emissions from Crater 2 became markedly ash-laden 4-7 June, with a plume rising a few kilometers above the crater and ashfalls on coastal areas 10 km NW. After the 7th, only weak to moderate vapour emissions and occasional Vulcanian explosions were noted from Crater 2.

"Activity at Crater 3 also waned after the first week in June, although more progressively. On the night of 7 June, intermittent explosions projected incandescent lava fragments to 250 m above the crater, while on 8 June there was weak steady glow over the crater. Intermittent explosions still occurred daily until the 24th, producing dark convoluting ash clouds that rose a few hundred meters above the crater.

"Seismic monitoring resumed on 11 June and showed only low-level activity throughout the rest of the month."

Information Contacts: P. de Saint-Ours, D. Lolok, and C. McKee, RVO.

July 1992 (BGVN 17:07) Cite this Report

Explosive activity and small lava flow

"Weak-to-moderate eruptive activity continued in July. Lava effusion at Crater 3 from 25 to 27 July or longer was associated with increased explosive activity late in the month.

"Activity at Crater 2 was at a low level 1-19 July with emissions of weak white vapour, occasionally blue or containing ash. A weak explosion probably associated with Crater 2 was heard on 1 July. There was no night glow during this period. Crater 2 was more active from 20 July until the end of the month. Loud-to-low rumbling noises and explosions were heard, accompanied by emissions of weak-to-moderate, occasionally thick, grey ash clouds. Weak night glow was observed from 20 July onward.

"Activity at Crater 3 was also low for most of the month, punctuated by occasional forceful emissions of grey-to-brown ash clouds, sometimes reaching more than 1 km above the summit. Activity increased to a moderate level from 25 July with audible explosive activity, night glow from the summit crater, and emission of a lava flow on the cone's N slope. The summit was obscured by clouds from 25 July and it was not clear whether the flow was still active. The explosion noises that started on 25 July continued until the end of the month. Light ashfalls ~10 km downwind from the volcano were noted on 5 and 22 July. Seismic activity was at a low level throughout the month despite the increase in visual activity."

Information Contacts: B. Talai and C. McKee, RVO.

August 1992 (BGVN 17:08) Cite this Report

Explosions and glow

"Moderate activity prevailed . . . throughout August. Activity at Crater 2 consisted of weak emissions of white and blue vapour with occasional rumbling sounds. From the 19th onward, the volume of gas and vapour emission increased, explosion sounds were heard intermittently, and a night glow was seen above the crater. Activity at Crater 3 was limited to occasional emission of white to grey vapour clouds. Seismicity remained low throughout the month, with only a few explosion shocks recorded daily."

Information Contacts: P. de Saint-Ours and C. McKee, RVO.

September 1992 (BGVN 17:09) Cite this Report

Ash emission and weak glow

"A moderate level of activity continued . . . in September. Activity at Crater 2 consisted of emission of white-to-grey vapour-and-ash clouds, occasionally with blue vapour. The emissions were accompanied by weak roaring noises. Weak night glow over the crater was seen 1-6 and 27 September. Emissions from Crater 3 were similar to those of Crater 2. Occasional weak explosions started on 6 September and continued until mid-September. No night glow was observed from the crater. Seismicity remained low throughout the month."

Information Contacts: B. Talai and C. McKee, RVO.

October 1992 (BGVN 17:10) Cite this Report

Vapor and ash emission

"Activity . . . was at a lower level during October than in previous months. Emissions from both craters consisted of weak-to-moderate white-to-grey vapour-and-ash clouds. Blue vapour was occasionally released from both craters during the latter part of the month. There was no glow observed throughout the month. Noises were heard from Crater 2 on the 31st. Seismicity remained low throughout the month."

Information Contacts: I. Itikarai, R. Stewart, and C. McKee, RVO.

November 1992 (BGVN 17:11) Cite this Report

Ash and incandescent tephra; possible new lava flow

"Activity at Langila's Crater 2 fluctuated in November. During periods of stronger activity, on 1-10, 15-17, and 23-26 November, moderate ash emissions occurred with eruption clouds rising several kilometres above the crater. This resulted in light ashfalls to at least 10 km downwind. At night, incandescent ejecta were visible in the eruption column. Detonations, roaring, and rumbling accompanied the activity. Between phases of stronger activity, white-grey, lightly ash-laden clouds were released less forcefully.

"For most of the month, Crater 3 released weak-to-moderate white-grey vapour-and-ash clouds. Blue vapour was also released. A brief phase of stronger activity took place 28-29 November when ash contents of the emissions were greater and eruption clouds rose several kilometres above the crater. There was an unconfirmed report of a new lava flow from Crater 3 on the 28th.

"Seismic activity appeared to reflect the visible fluctuating explosive activity at Crater 2. Up to 15 explosion earthquakes/day were recorded. During the brief phase of stronger Crater 3 activity, periods of harmonic tremor were recorded."

Information Contacts: C. McKee, RVO.

December 1992 (BGVN 17:12) Cite this Report

Ash ejection and glow

"Moderate eruptive activity continued at Langila during December. Emissions from Crater 2 throughout the month consisted of weak-to-moderate white vapour-and-ash clouds, accompanied by occasional forceful emission of thick dark-grey and brown ash plumes rising several kilometers above the summit. Fine ashfalls were reported on 4, 12, 19, and 25 December to the N and SE of the volcano. Weak explosion sounds were heard at the observation post (10 km away) throughout the last 3 weeks of the month. Steady, weak crater glow was seen on 5, 7, 19-20, and 22 December.

"Activity at Crater 3 was similar to that in November. Emissions consisted of weak-to-moderate white-grey vapour-and-ash clouds. Thick grey and brown plumes were forcefully emitted on 1, 6, and 10 December. Blue vapour was also intermittently released. Weak explosion and rumbling noises were heard on the 5th-7th. There was no night glow visible throughout the month.

"Seismicity increased slightly during the month and continued to reflect the eruptive activity at Crater 2. On average, 31 explosion earthquakes/day were recorded . . . ."

Information Contacts: H. Patia and B. Talai, RVO.

January 1993 (BGVN 18:01) Cite this Report

Ash ejections and glow continue

"Activity remained at a moderate level in January, very similar to the activity in December. Emissions from Crater 2 consisted of weak-to-moderate white vapour-and-ash clouds. Occasionally, forceful emissions of thick dark-grey ash-laden clouds formed a column several hundred metres high at the summit. Explosion and rumbling sounds usually accompanied these Vulcanian explosions. Fine ashfalls were reported on the SE side of the volcano on a few days. A steady, weak night glow was seen over the crater during the second half of the month, with incandescent Strombolian projections to 100 m on 23-24 January. Activity at Crater 3 was at a very low level throughout the month, consisting only of the gentle release of small volumes of white vapour, with some blue vapour 30-31 January. Seismicity remained low, with only a few explosion earthquakes recorded daily."

Information Contacts: R. Stewart, P. de Saint-Ours, and C. McKee, RVO.

February 1993 (BGVN 18:02) Cite this Report

Small Vulcanian eruptions

"Langila was more active in February than it had been since February-March 1992, with strong, sub-continuous Vulcanian activity from Crater 2, and a few days of eruptive activity at Crater 3.

"Although the volcano was covered in atmospheric clouds for the first week of the month, strong explosion and rumbling sounds from 5 February onward suggested renewed activity. When visible (after the 8th), Crater 2 displayed a dark column of ash-laden vapour that was forcefully released, convoluting and rising ~1 km above the crater. At night on 12 February, incandescent ejecta were visible in the Vulcanian eruption cloud, with ballistic trajectories rising up to 500 m above the crater. The strength of the eruption seemed to decrease after the 12th, with only night glow or mild incandescent projections 15-18 February. During the remainder of the month, Crater 2 released a steady white-gray plume of ash-laden vapour.

"Activity at Crater 3 was mild for the first half of the month, with moderate or weak emission of thin white vapour. Discrete Vulcanian explosions resumed on 12 February. By the 15th, the plume was forcefully rising several hundred meters above the crater. The plume was accompanied by strong explosion sounds and incandescent projections of increasing strength 15-18 February (maximum 400 m above crater). This activity decreased by the next day, with mainly weak white or blue vapour, and only occasional ash-laden emissions on 21-22 and 28 February.

"The seasonal NW wind carried fine ash over villages 8-18 km to the SE. Field inspection showed ~1 mm of ash accumulation in that area."

Information Contacts: R. Stewart, P. de Saint-Ours, and C. McKee, RVO.

March 1993 (BGVN 18:03) Cite this Report

Explosions send incandescent material 80 m above summit

"Eruptive activity . . . remained at a moderate-to-strong level during March. Crater 2 continued to release white-grey ash-laden vapour at a moderate-to-strong rate and occasional thick dark grey-to-brown ash clouds. These emissions were accompanied by weak-to-loud explosion noises. From the 23rd until the end of the month, continuous dark grey ash clouds rose several hundred meters above the summit. Fine ashfall was reported downwind (SE). These emissions were accompanied by weak explosions and rumbling noises. The summit area was cloud-covered on most nights during the first half of the month. However, incandescent Strombolian projections were visible on the 4th and 5th. On 15, 19-20, and after 23 March until the end of the month, steady weak to occasional bright fluctuating glow was visible. Incandescent Strombolian projections up to 80 m above the summit were seen on the 27th and 29th.

"Activity at Crater 3 was mild during the month, with weak-to-moderate emissions of white and blue vapour accompanied by the occasional forceful ejection of moderate-to-thick dark grey ash clouds rising several hundred meters above the summit. During the last 3 weeks of the month the emissions were accompanied by occasional weak explosion noises. Night glow and incandescent projections were seen on 15, 16, and 19 March. "A slight increase in seismicity during the month was recorded by the seismograph 9 km N of the volcano. About 200 Vulcanian explosion earthquakes were recorded during the month with the highest daily total of 24 events on both the 23rd and 24th."

Information Contacts: H. Patia, R. Stewart, and C. McKee, RVO.

April 1993 (BGVN 18:04) Cite this Report

Strombolian explosions continue

"Eruptive activity was at a moderate-to-high level during April. A total of 134 Vulcanian explosion earthquakes was recorded, with the highest daily total of 17 events on 5 April.

"Incandescent Strombolian projections to 300 m above Crater 2 were seen on 2, 4, 5-10, and 23 April. Steady, weak glow was observed on 11, 19, 20, 24, and 26 April. Explosion and rumbling noises were heard throughout the month. Dark grey ash columns and moderate-to-strong white-grey vapour were released every day. Some ashfall to the SE and NW of the volcano was reported.

"Crater 3 was active until 13 April, producing moderate-to-strong ash emissions accompanied by deep explosion noises. Emissions then stopped until 22 April when weak blue and white vapours appeared. Emissions stopped again on 26 April. No glow or incandescent ejections were observed."

Information Contacts: N. Lauer, R. Stewart, and C. McKee, RVO.

May 1993 (BGVN 18:05) Cite this Report

Explosive activity declines

"Activity declined to a moderate level in May after about 3 months of relatively strong explosive eruptions. The latest period of incandescent lava ejections and night glow at Crater 2 ended on 9 May, although there were still moderate emissions of thin-to-thick grey ash-vapour clouds. Occasional dark ash columns resulted in light ashfalls on the N and NW sides of the volcano. Weak explosions and low rumbling noises were heard at the beginning of May, but subsided after the 19th. The number of Vulcanian explosion earthquakes recorded in May dropped to 70, compared to 134 in April. Activity from Crater 3 consisted of weak white vapour emissions. No glow was observed, and the crater remained silent."

Information Contacts: I. Itikarai, P. de Saint-Ours, R. Stewart, and C. McKee, RVO.

September 1993 (BGVN 18:09) Cite this Report

Fluctuating ash and vapor emissions

"Activity declined to a low level in June and remained low through July. Crater 2 intermittently released white-grey ash and vapour clouds in small to moderate amounts. The crater was silent throughout the month, as it has been since the end of May (BGVN 18:05). No glow was observed. The number of Vulcanian explosion earthquakes showed a marked decline to 19 in June from 70 in May and 134 in April. Crater 3 continued to occasionally release weak emissions of white vapour. No activity was recorded from Crater 3 in July.

"Langila's activity increased slightly in August. Crater 2 released white-grey vapour and ash for most of the month. Explosions producing ash falls in inhabited areas were recorded on 6, 8, 20, and 25-26 July. Crater 3 emissions consisted of weak blue vapour.

"Activity appeared to decline in September. Crater 2 emitted weak to moderate amounts of vapour and ash. On a few occasions, falls of ash took place in inhabited areas about 10 km downwind from the vent. Activity at Crater 3 continued at a low level with weak emissions of white and blue vapours. Seismicity was low throughout the month."

Information Contacts: C. McKee, N. Lauer, L. Sipison, B. Talai, R. Stewart, and D. Lolok, RVO.

October 1993 (BGVN 18:10) Cite this Report

Moderate eruptions at Craters 1 and 2

"After 5 months of mild activity, stronger eruptions resumed in mid-October from both Craters 2 and 3. During the first weeks of the month, activity at Crater 2 consisted of occasional Vulcanian explosions rising to a few hundred metres above the crater and causing minor ash fall at the summit area. Crater 3 released weak, thin white and blue vapours.

"By 15 October, ash-laden emissions from Crater 2 became continuous. On the 17th, rumbling noises and bright night glow indicated a return to more sustained eruptive activity. The next day, Crater 3 released grey ash and incandescent lava clots to a height of 20 m, with continuous rumbling sounds. The eruptions from both craters remained moderate, more Vulcanian at Crater 2 and more Strombolian at Crater 3. Night glow was not observed at Crater 2 after the 24th, although dark ash emission persisted. Loud Strombolian explosions occurred at Crater 3, although incandescent ejections remained small. On the 30th, a lava flow emerged from the W side of Crater 3 and progressed northward, in a dry stream channel, on the W side of the lava field at the N foot of the volcano. The following night, Strombolian ejections reached 100 m above the crater rim. A particularly large Vulcanian explosion on the afternoon of 31 October produced a dark column that rose to ~10 km.

"Both seismographs were unoperational before 28 October. From that day onward, the level of seismicity was relatively high, with up to 44 explosion events/day."

Information Contacts: C. McKee, P. de Saint-Ours, and I. Itikarai, RVO.

November 1993 (BGVN 18:11) Cite this Report

Eruptive activity continues at moderate level

[Volcanism] continued during November at more moderate levels. Activity from Crater 2 consisted of moderate Vulcanian explosions accompanied by loud detonations. Some of these ash-laden emissions rose several hundred metres above the crater rim producing light ashfalls on the N and NW sides of the volcano. Steady weak red glow from Crater 2 was observed on 15, 21, 22, and 23 November. In the first week of November, Crater 3 activity consisted of weak-to-moderate Strombolian explosions and weak lava effusion. After the 7th, the activity changed to Vulcanian explosions only, accompanied by weak-to-loud detonations. Seismicity showed a moderate level of activity with 1-46 recorded explosion events/day."

Information Contacts: I. Itikarai, and C. McKee, RVO.

December 1993 (BGVN 18:12) Cite this Report

Moderate eruptive activity continues

"The moderate eruptive activity . . . continued unabated in December. Both craters erupted spasmodically throughout the month, generating moderate volumes of ash. The activity may have been stronger at Crater 3 judging by the reported loud explosions there and ejections of incandescent lava-fragments that were seen on a few nights at mid-month. By contrast, Crater 2 explosions were muffled and only glow above the crater was seen at night. Seismicity was dominated by explosion events at rates of up to ~40/day."

Information Contacts: C. McKee and R. Stewart, RVO.

January 1994 (BGVN 19:01) Cite this Report

Intermittent eruptions produce moderate volumes of ash

"Both craters continued their spasmodic Vulcanian eruptions throughout January, generating moderate volumes of ash. Activity was stronger at Crater 3; explosions were heard intermittently and produced ash clouds rising a few hundred meters above the crater before being dispersed. In contrast, Crater 2 explosions were muffled and ash emission less frequent. Being the rainy season, the craters were covered by atmospheric clouds on most nights, but incandescent projections were seen at Crater 3 on 3 January. A steady red glow above Crater 2 was seen on 3 and 30 January. Seismic activity was relatively high, with up to 76 explosion events/day . . . ."

Information Contacts: D. Lolok and P. de Saint-Ours, RVO.

February 1994 (BGVN 19:02) Cite this Report

Loud explosions and thin gray ash emission

"Crater 3 continued to produce mild spasmodic eruptions while Crater 2 activity was at a low level. During the first week of February, loud explosions at Crater 3 accompanied the release of grey ash, moderate to thin in volume, that rose several hundred metres above the summit. The intensity of explosions during the rest of the month was much lower, but the amount of ash emitted remained steady. Night glows were not observed from Crater 3, although it was often obscured by atmospheric clouds. Crater 2 activity was low during most of the month with the release of thin pale grey ash. From 7 to 10 February there were forceful emissions of moderately thick grey ash. Weak crater glow was seen on a few nights when the summit was clear of atmospheric clouds. Seismic activity during February remained at a moderate level with minor fluctuations."

Information Contacts: B. Talai and C. McKee, RVO.

March 1994 (BGVN 19:03) Cite this Report

Explosion sounds and small ash emissions

"Crater 2 and Crater 3 both produced mild spasmodic eruptions. Crater 2 released small volumes of ash during 11-18 March, accompanied by deep roaring sounds and incandescent projections on the 15th and 16th. Crater 3 generated occasional explosion noises during 1-10 March, and released small volumes of ash on 3, 10, 13, 15, 17, 27, and 29 March. The ash emissions on 15 March were accompanied by loud explosion noises and incandescent projections. Low explosion noises were also heard on the 29th. There was no seismic monitoring at Langila in March."

Information Contacts: B. Talai and C. McKee, RVO.

April 1994 (BGVN 19:04) Cite this Report

Fine ashfall after one explosion; red glow seen and explosion noises heard

"Observations were conducted during 1-17 and 23-27 April. The level of activity was slightly lower than in March. Emissions from Crater 2 consisted mainly of thin-to-moderate white-grey vapour-and-ash clouds. Explosion noises were heard on 4, 5, and 17 April, and weak rumbling noises were heard during 23-27 April. The explosion on 4 April produced a thick ash column that rose a few hundred metres above the crater and resulted in fine ashfall on the NW side of the volcano. Steady weak red glow was observed on 23-24 April. Crater 3 released emissions of thin white vapour with occasional low ash content. Seismic activity was at a low level."

Information Contacts: I. Itikarai, and C. McKee, RVO.

May 1994 (BGVN 19:05) Cite this Report

Ash columns noted on six days in May

Both craters at Langila continued at a low activity level in May. Emissions from Crater 2 consisted of weak-to-moderate white-gray vapour and ash clouds. Occasional forceful ejections of thick, dark-grey ash columns accompanied by explosion noises were reported on the 2nd, 7th, 9th, 20th, 29th, and 31st. Fine ashfall was reported on the 2nd and 20th on the NW side of the volcano. A steady weak red glow was visible on the 5th. Crater 3 released thin white vapour with very low ash content accompanied by thin blue vapor. Seismic activity was at a low level at the beginning of the month. No seismic recording was achieved after the 3rd because of equipment failure."

Information Contacts: I. Itikarai and C. McKee, RVO.

June 1994 (BGVN 19:06) Cite this Report

Ash columns from both active craters

"The relatively low level of activity . . . continued throughout June. Emissions from Crater 2 consisted of weak-to-moderate white-grey vapour-and-ash clouds, associated with blue vapour on the 15th only. Forceful ejections of thick grey ash columns rising several hundred metres above the crater rim were reported on 1, 6, and 8 June. These emissions resulted in fine ashfalls NW and SE of the volcano. On these occasions, as on most days after 16 June, weak explosion noises were heard. Steady weak red glow was visible from the 6th until month's end.

"Crater 3 released thin white vapour with very low ash content, and occasionally thin blue vapour. On 27 June, a moderately thick white-grey ash column rose to a few hundred metres above the summit and dispersed fine ash to the NW side of the volcano. It was accompanied by one deep explosion at 0901. There was no visible glow throughout the month.

"Seismographs were unfortunately faulty until 29 June. When back in operation, they recorded a low level of activity comparable to that of early May."

Information Contacts: D. Lolok, R. Stewart, I. Itikarai, P. de Saint-Ours, and C. McKee, RVO.

July 1994 (BGVN 19:07) Cite this Report

Thick ash clouds from Crater 2 accompanied by explosion sounds

"Eruptive activity at Crater 2 continued during July, while Crater 3 activity was at a low level. Throughout the month, Crater 2's normal moderate emissions of thin white-grey vapour were disrupted by forceful ejections of thick, mushroom-shaped, grey-brown ash clouds accompanied by low explosion and rumbling sounds. These caused fine ashfall NW of the volcano. On 16 and 22 July, the ash clouds rose several thousands of meters above the crater. Steady weak night glow was reported on 26 July and there was fluctuating weak-bright glow on the 29th. Crater 3 continued to emit small volumes of mostly white vapour, sometimes with blue and grey vapour. There were no audible sounds or night glow reported during July. Seismic activity throughout the month remained at a low level with between 1 and 7 small low-frequency earthquakes/day."

Information Contacts: B. Talai, R. Stewart, and C. McKee, RVO.

August 1994 (BGVN 19:08) Cite this Report

Explosions produce thick eruption columns and light ashfall

"Eruptive activity at Crater 2 continued in August. Except for a quiet period during 1-11 August, on most days thick columns of mushroom-shaped grey-brown ash clouds were released. Light ashfall in coastal areas downwind was reported on 12 and 26 August. One explosion noise was heard on the 12th, and occasional rumbling noises were heard on the 17th and 23rd. Steady weak red glow was seen on 1 and 15 August.

"Crater 3 activity was generally low. Throughout August, Crater 3 produced weak emissions of thin, pale-grey and occasionally blue vapour. After the 26th the volume of blue emissions became moderate. The 30th marked the beginning of occasional moderate to thick emissions of grey-brown ash clouds producing light ash fall on the N and NW sides of the volcano.

"Seismicity was low throughout the month. Daily totals of volcanic earthquakes were between 1 and 5."

Information Contacts: I. Itikarai, R. Stewart, and C. McKee, RVO.

October 1994 (BGVN 19:10) Cite this Report

Moderate intermittent Vulcanian explosions from both craters

Eruptive activity in September and October at both craters consisted of moderate and intermittent Vulcanian explosions. Crater 3 was active during the first nine days of the month. It released a moderately thick vapor plume, with occasional dark gray ash clouds, accompanied by explosions and rumbling sounds, and resulting in light ash falls onto the NW flank and coastal villages. For the remainder of September and October, it only emitted very thin wisps of vapor, occasionally accompanied by blue vapor.

At Crater 2, background levels of moderate white and blue vapour emissions continued, and very weak night glow was seen on 7 September. However, activity picked up on the 12th and 13th with occasional dark ash-laden, convoluting Vulcanian explosions. Similar low-level eruptive activity resumed on 15-18, 24, and 28-29 September.

A good correlation could be seen between the level of seismicity and volcanic activity in September. The two local seismographs recorded 2-5 explosive events/day during 1-9 September at Crater 3, and then 2-8 events/day during each of the intermittent phases of activity at Crater 2. Seismicity remained at a low level throughout October.

Emissions from Crater 2 in October consisted of thin white vapour with occasional dark gray, ash-laden convoluting columns rising up to a few hundred meters above the crater. Fine ash fell on downwind coastal areas. Weak night glow accompanied these explosions on 3, 6, 9, 21-22, and 30 October.

Information Contacts: C. McKee and P. de Saint-Ours, RVO.

November 1994 (BGVN 19:11) Cite this Report

Moderate intermittent Vulcanian explosions

"Continuing the trend of previous months, eruptive activity consisted of moderate and intermittent Vulcanian explosions from Crater 2. During most of November, activity at Crater 2 consisted of noiseless emission of thin white vapour. Occasionally (on 4, 6-8, 15, 18, and 27-29 November), weak explosions were heard and accompanied the rise of dark-grey ash-laden columns to a few hundred meters above the crater. Some of these explosions were large enough to be recorded by a seismometer 9 km away. Fine ashfall was reported in downwind coastal areas. Between 14 and 27 November, weak night glow was seen and the activity was accompanied by low to loud rumblings. Crater 3 released only fumarolic emissions, occasionally accompanied by blue vapour."

Information Contacts: B. Talai, R. Stewart, and P. de Saint-Ours, RVO.

December 1994 (BGVN 19:12) Cite this Report

Weak to moderate vapor emissions continue from Crater 2

"The eruptive activity . . . declined in the first half of December. There were a few Vulcanian explosions from Crater 2 in the first half of the month, and virtually no activity during the second half of the month. Crater 3 continued to release only fumarolic emissions, with occasional wisps of blue vapour. Seismicity remained low throughout the month.

"Activity at Crater 2 in the first two weeks consisted mainly of weak-moderate emissions of white-grey vapour. Roaring and rumbling sounds were heard on 2 and 3 December; fluctuating glow was observed at night. A deep explosion heard on 7 December generated an ash column several hundreds of metres above the crater rim; there was fine ashfall to the SE. During 10-13 December there were occasional rumbling, roaring, and explosion noises, and steady weak glow was seen on 10 and 13 December. From 14 December until the end of the month, no sounds were heard and weak to moderate emissions again consisted of white-grey vapour. Steady weak night glow was seen on 23, 28, 29, and 31 December."

Information Contacts: D. Lolok, R. Stewart, and B. Talai, RVO.

January 1995 (BGVN 20:01) Cite this Report

Vapor-and-ash clouds; explosions and rumbling noises

"Emissions at Crater 2 consisted mainly of white-grey vapour-and-ash clouds in low-moderate volumes. Fine ashfall to the SE of the volcano was reported on 3 January. Occasional rumbling noises accompanying the emissions were heard intermittently throughout the month. Low-loud explosions were heard on 3, 30, and 31 January. A weak glow was seen on most nights during the first week and on 21 and 30 January around the crater rim. Activity at Crater 3 was mostly confined to weak-moderate emissions of white vapour accompanied by pale grey ash clouds and wisps of blue vapour on 26 and 28 January. The seismograph was not operational during January."

Information Contacts: H. Patia, R. Stewart, and B. Talai, RVO.

February 1995 (BGVN 20:02) Cite this Report

Occasional explosions from Crater 2 generate dark clouds and ashfall

"Activity during February continued to be focused at Crater 2, at the moderately low level observed since December. Emissions consisted mainly of white-to-grey vapour-and-ash clouds in low or moderate volumes. Occasionally, an explosion produced a larger and darker cloud that rose a few hundred meters above the crater and produced fine ashfall SE of the volcano. Rumbling noises accompanying the emissions were heard intermittently throughout the month, and weak glow was seen on most clear nights. Activity at Crater 3 consisted essentially of fumarolic emission of thin white vapour. The seismograph was not in operation during February."

Information Contacts: P. de Saint-Ours, R. Stewart, and B. Talai, RVO.

March 1995 (BGVN 20:03) Cite this Report

Moderate emissions and explosions from Crater 2

"Monitoring was temporarily discontinued on 18 March. Until that time activity at Crater 2 was at a moderate level, similar to that observed in February, while Crater 3 showed a low level of activity. Emissions from Crater 2 were mostly white vapour, weak to moderate in volume. Occasionally grey ash clouds were emitted. Light ash fall took place around the crater. One loud explosion was heard on 8 March with weak explosions on the following two days and low rumbling sounds on the 16th. Steady weak night glow was observed on 16 and 17 March. Crater 3 released very thin to occasionally moderately thick white vapour. Thin blue vapour was observed on 1 and 7 March. There were no audible sounds and no night glows. Both seismographs remained inoperative throughout the month."

Information Contacts: B. Talai, RVO.

April 1995 (BGVN 20:04) Cite this Report

Ash clouds to several hundred meters above the crater

Monitoring of Langila resumed on 3 April following a lapse from 18 March to 2 April. Up to that time, activity at Crater 3 remained low and activity at Crater 2 continued at a moderate level. After the lapse in monitoring, Crater 2 continued to emit white vapors in low to moderate volumes. Gray ash clouds were occasionally emitted to several hundred meters above the crater. Occasional rumbling sounds and night time glows were normally associated with the ash emissions. Loud explosions were heard on 3 and 30 April. Ashfall NW of the volcano (in the Kilenge area) was reported on 11 April. Crater 3 released thin white vapor accompanied by wisps of blue vapor on 12, 14, 21, and 27 April. There were neither audible sounds nor night glows. Both seismographs remained inoperative during the month.

Information Contacts: David Lolok and Ben Talai, RVO.

May 1995 (BGVN 20:05) Cite this Report

Slightly increased activity at Crater 2, but still at moderate levels

"Throughout May, Crater 2 produced forceful moderate to strong emissions of white-grey vapour and ash as well as occasional dark mushroom-shaped ash clouds. Many of the ash clouds rose several hundred metres above the crater rim, resulting in light ashfall to the N and NW on most days of the month. Some of the forceful ash emissions were accompanied by weak (and occasionally strong) detonations, but more frequently by rumbling noises. A strong explosion on the 26th was accompanied by lighting flashes. Projections of red incandescent lava fragments were observed on the 9th and 26th, and weak red summit glows were observed on 3, 23, 25, and 28-29 May. Activity at Crater 3 was at a very low level, mainly gentle emissions of thin white vapour. There were some days when no vapour emissions were observed. Neither audible noises nor summit glow were noted. One seismograph was restored and began operating again on 29 May."

Information Contacts: Ima Itikarai and Ben Talai, RVO.

June 1995 (BGVN 20:06) Cite this Report

Moderate emissions with some ash clouds

Eruptive activity was centered at Crater 2 throughout the month, and maintained a moderate level slightly lower than in May. These continuous to sub-continuous emissions were accompanied by occasional forceful, mushroom-shaped, light gray to brown ash clouds rising several hundreds of meters above the crater rim. Fine ashfalls extended ~10-15 km from the volcano to the N and NW coasts. Weak deep explosion and rumbling sounds were heard on 13, 20, 22, 23, and 30 June, with weak summit glow seen only on 30 June.

Activity at Crater 3 remained very quiet throughout the month although thin white vapor wisps were observed on 11, 14, and 27 June. Neither audible noises nor summit glow were noted. Throughout June no seismicity was recorded.

Information Contacts: Ima Itikarai and Ben Talai, RVO.

July 1995 (BGVN 20:07) Cite this Report

Intermittent large explosions

Moderate eruptive activity continued at Crater 2 throughout July; intermittent large explosions alternated with weaker ash and vapor emissions. The larger explosions rose several hundred meters above the crater rim, dropping ash on the downwind (N-NW) side of the volcano. The sounds from these large explosions ranged from loud detonations to deep rumblings. Crater glow was observed on 1 and 16 July. Activity at Crater 3 remained very low, with only weak white vapor emissions. The seismograph was inoperable throughout the month.

Located on the N coast of western New Britain, Langila consists of four overlapping composite cones. These cones lie on the E side of the inactive Talawe volcano. An extensive lava field extends from the cones toward the coast. Langila is one of New Britain's most active volcanoes.

Information Contacts: Ben Talai, RVO.

August 1995 (BGVN 20:08) Cite this Report

Intermittent Vulcanian explosions and weaker ash-and-vapor emissions

During August, intermittent Vulcanian explosions interspersed with weaker ash-and-vapor emissions continued at Crater 2. Larger explosions rose several hundred meters above the crater rim and resulted in ashfalls on the downwind (N-NW) side of the volcano. Observers heard low detonations to deep rumblings; on 4, 5, and 17 August they saw weak, steady crater glow. No activity was seen from Crater 3. The seismographs remained inoperative in August.

Information Contacts: Patrice de Saint-Ours and Ben Talai, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

October 1995 (BGVN 20:10) Cite this Report

Ash-bearing eruption columns rise hundreds of meters

The increased eruptive activity at Crater 2 that began during late September continued throughout October. The activity was marked by intermittent audible explosions. The bigger explosions developed plumes that rose several hundred meters above the summit crater, resulting in ashfalls on the volcano's N-NW side. Langila produced steady but weak crater glow on most nights during October; it threw incandescent lava fragments on 23-24, 26, and 31 October. Crater 3 was quiet, only giving off weak white emissions towards late October. Seismic recording restarted on 5 October after both seismographs had been inoperative since January 1995. October seismic activity was moderate.

Information Contacts: Ben Talai, RVO.

December 1995 (BGVN 20:11) Cite this Report

Ongoing eruptions lead to detectable ashfalls 10-15 km away

Throughout November-December, Crater 2 continued to emit white-to-gray ash and vapor, with plumes rising up to several hundred meters above the crater. During November, ashfalls reached 10-15 km on the N-NW flank; these eruptions were accompanied by audible explosions and rumbling. The eruptions threw incandescent projectiles during the first half of both November and December, and steady crater glow took place on most November nights and on 9-11 December. Crater 3 remained quiet. The greatest December activity, during the 23rd through the 26th, had emissions similar to those in November, but plumes rose somewhat higher (up to 1 km above the crater) and ash fell 10-15 km SE and SW.

Information Contacts: Ben Talai, H. Patia, D. Lolok, and C. McKee, RVO.

February 1996 (BGVN 21:02) Cite this Report

Ash-and-vapor clouds and occasional night glow

Activity at Crater 2 was low to moderate in January and moderate in February. During this time, the explosions produced thick white-gray ash-and-vapor clouds; these usually blew SE over unpopulated areas. Eruption sounds varied between rumblings and detonations. On most February nights, observers saw variable glow over Crater 2 and, on 2, 8, and 23 February, ejection of incandescent lava fragments. During January and February, Crater 3 was inactive, but moderate seismicity prevailed. The daily total of explosion earthquakes during February ranged between 0 and 5.

Information Contacts: Ima Itikarai and Ben Talai, RVO.

March 1996 (BGVN 21:03) Cite this Report

Vulcanian explosions continue

Moderate explosive activity continued at Crater 2 during March, however, there was possibly a slight decline compared to last September. Intermittent Vulcanian explosions released ash clouds that rose several hundred meters above the crater. These explosions resulted in minor ashfalls to the volcano's SE. A weak but steady crater-glow was observed on a few nights. In accord with these observations, 6-30 daily explosion earthquakes registered at a station 4 km away. There was no visible activity from Crater 3.

Information Contacts: Ben Talai, RVO.

April 1996 (BGVN 21:04) Cite this Report

Occasional ash-and-vapor clouds and night glows

Moderate eruptive activity continued at Crater 2 during April. As in recent months, the activity consisted of intermittent moderate Vulcanian explosions that produced variable density, white-to-gray ash-and-vapor clouds rising several hundred meters above the rim. The clouds were blown to the N, NW, and SE of the volcano, resulting in fine ashfalls. Occasional eruption sounds consisted of explosion noises and rumblings throughout the month. Crater-glow of variable intensity was seen on most nights during the month. The seismic station 4 km from the volcano registered a daily range of 10-40 explosion earthquakes. Crater 3 was quiet during the month.

Information Contacts: H. Patia, RVO.

May 1996 (BGVN 21:05) Cite this Report

Intermittent Vulcanian explosions produce ash-and-vapor clouds

Crater 2 activity continued in May as in past months (BGVN 21:04) with intermittent Vulcanian explosions producing thin-to-thick white-to-gray/brown ash-and-vapor clouds. These clouds rose several hundred meters above the rim before being blown to the N, NW, and SE and producing fine ashfalls. Occasional explosions were heard. Glows of variable intensity were seen on most nights during the first three weeks. Weak projections of incandescent lava fragments were observed on 12 and 14 May. A daily range of 10-50 explosion earthquakes was recorded at the seismic station until it became non-operational on 24 May. Crater 3 remained quiet apart from a single emission of very thin white/gray vapor on 7 May.

Information Contacts: D. Lolok and C. McKee, RVO.

June 1996 (BGVN 21:06) Cite this Report

Continued weak eruptions with increased seismicity in June

During June, white-gray or brown ash and vapor clouds emitted from Crater 2 rose to several hundred meters above the crater rim. Fine ash was mostly blown to the NW and occasionally to the SE and NE. Rumbling noises were heard throughout the month. During the first half of June, night glow was seen only on 5 June, but weak red glow was observed on most nights of the second half of the month. Weak to moderate projections of glowing lava fragments were observed on the nights of 17, 18, 19, and 21 June. Crater 3 remained quiet during June.

Information Contacts: D. Lolok, and C. McKee, RVO.

July 1996 (BGVN 21:07) Cite this Report

Low-level activity persists

During July, Crater 2 continued its low-level eruptive activity and Crater 3 remained quiet. Crater 2 emitted gray to brown ash clouds, which rose several hundred meters above the crater. The ash clouds were blown to the NW and produced light ashfall. The emissions were accompanied by rumbling and explosion sounds. On most nights in July, variable glows were observed around the crater. Small incandescent lava fragments were ejected on 12 July.

Information Contacts: B. Talai, D. Lolok, and C. McKee, RVO.

August 1996 (BGVN 21:08) Cite this Report

Several mild explosions and crater glow

Although there was a lull in activity at mid-month, mild eruptive activity continued at Crater 2 in August. Moderate intensity, frequent ash emissions accompanied by rumbling and detonations took place from the beginning of the month until the 14th. In the period 15-20 August, the emissions were usually only white vapor. However, on the 16th there were two explosions. Frequent ash emissions resumed on the 21st with occasional stronger explosions. Throughout the month there were sightings at night of steady weak red glow above the crater. The Langila seismographs remained inoperative in August.

Information Contacts: C. McKee and B. Talai, RVO.

September 1996 (BGVN 21:09) Cite this Report

Moderate Vulcanian activity; vapor-and-ash clouds, ashfall, crater glows

Crater 3 remained quiet during September. Moderate Vulcanian activity at Crater 2 continued until 14 September; after then the activity declined to weak emissions of thin, white vapor. Emissions from Crater 2 produced thin white to thick gray vapor-and-ash clouds, which rose to a few hundred meters above the crater rim. Ash-laden emissions were commonly accompanied by low rumbling sounds. On 4-6, 10, and 13-14 September, strong explosions resulted in light ashfall on populated areas to the NW. Weak, steady crater glows were observed on most nights before 14 September. The Langila seismographs were inoperative during September.

Information Contacts: Chris McKee and Ben Talai, RVO.

December 1996 (BGVN 21:12) Cite this Report

Eruptions continue during October-December

Eruptive activity at Crater 2 continued during October-December. The activity pattern of 7-26 October was similar to that during January-September. Emissions included thin, white to thick, gray vapor-and-ash clouds. The ash clouds rose ~1-2 km above the crater. Ashfall was observed on 8-22 October on the N, NW, and SE sides of the volcano. Weak, steady, red glows were seen on the nights of 7, 12-13, 20-21, and 26 October. Projections of red incandescent lava fragments occurred on the nights of 8-10 and 17 October. After 26 October eruptive activity declined to emissions of thin, weak, white vapor. During November and December, activity at Crater 2 consisted of emissions of thin, weak, white vapor, and, occasionally, moderate ash clouds. Light ashfall was observed on 5 and 11-12 November on the N, NW, and SE sides of the volcano.

Crater 3 remained quiet during October-December. Thin, weak, white vapor began to emit on 1 December. Seismic monitoring was conducted only between 11 November and 4 December. Seismicity was low during this period.

Information Contacts: B. Talai, I. Itikarai, and P. de Saint Ours, RVO.

January 1997 (BGVN 22:01) Cite this Report

Small January plumes; February plumes reach 11 km altitude

Throughout January activity at Crater 2 continued at a low level. Although on most days, Crater 2 only occasionally released pale gray ash clouds, from 9 to 19 January, darker gray clouds were emitted. These were occasionally accompanied by weak rumbling sounds and the emission of glowing lava fragments. The ash clouds seldom rose higher than ~2.5 km, although they occasionally reached ~4 km altitude. They blew to the SE, resulting in light ashfall. During January, Crater 3 released only fumarolic white vapors. No seismic recording took place during the month.

During 11-12 February at least five aviation reports gave warnings to pilots (SIGMETs) for Langila's plumes. The reports indicated the plumes reached at least 10.7 km altitude on 11-12 February. Although some reports described W-drifting plumes, one report at 1745 on 12 February described a "tight radius" plume that consisted of a ". . . solid core of discernible ash up to [10.7 km altitude]."

Information Contacts: B. Talai, D. Lolok, P. de Saint-Ours, and C. McKee, RVO.

February 1997 (BGVN 22:02) Cite this Report

Eruptions to about 11-km altitude create aviation risks

Crater 3 remained quiet during February, but Crater 2 continued to generate Vulcanian explosions; in some cases ash columns rose to 6 km. During early February observers noted loud detonations, roaring, and rumbling. About mid-month bad weather obscured the volcano. From 21 February until the end of the month the explosions seemed weaker. During February there was no seismic recording.

Aviation sources reported ash plumes on 11-12 February (BGVN 22:01) to at least 10.5 km altitude. Since then, Tom Casadevall learned of an aircraft encounter with an ash cloud that was presumably from Langila. The commercial 747 was en route on R-204 from Seoul to Brisbane. The encounter, 1129 GMT on 12 February, occurred at an altitude of ~11 km (37,000 feet) at a location [~550 km SSW of Langila, near 8.75°S, 144.5°E]. The aviator's observations follow.

"Outside air temp[erature] was at -48°C, suddenly [outside air temperature] increased to - 38°C. Smell of sulfur was experienced in the cockpit. No change in engine parameters. Crew attempted to contact [air traffic control] to change course, but were unable to make radio connection due to poor signal. After 5 minutes, flight exited dust cloud and continued on to Brisbane. Safe and uneventful landing. Upon aircraft return to Seoul, all engines were inspected per [Airline Maintenance Manual] for volcanic ash ingestion. Inspection reports found no evidence of problems."

Volcanic ash plumes pose hazards to aircraft; for example, the ash, which is not discriminated from weather clouds by on-aircraft instruments, can seriously damage jet engines.

Information Contacts: B. Talai, H. Patia, D. Lolok, P. de Saint Ours, and C. McKee, RVO; Geoff Garden, Bureau of Meteorology, Australia; Thomas J. Casadevall, USGS.

April 1997 (BGVN 22:04) Cite this Report

Fluctuating activity, with variable March and April plumes

Although visibility was limited by a cyclonic depression during much of March, on the 22nd an ash plume rose to 3 km. Then, during the first ten days of April a brief lull took place as Crater 2 typically issued moderate volumes of white vapor and produced isolated weak explosions.

Between 11 and 16 April, ash emissions became more frequent. During 17-20 April, emissions consisted of continuous, thick pale brown to dark gray clouds. For the remainder of the month the emissions occasionally consisted of thin to thick ash of pale brown to pale gray color.

Crater 3 exhibited weak fumarolic activity in April. The seismographs were inoperative during March and April.

Information Contacts: B. Talai, H. Patia, D. Lolok, P. de Saint Ours, and C. McKee, RVO.

May 1997 (BGVN 22:05) Cite this Report

Late-May eruptions send plumes up to 4.5 km elevation

Vulcanian explosions resumed in late May. During the first 3 weeks of the month Crater 2 released moderate volumes of steam. Then, an explosion on the 22nd at 1510 produced dark gray ash clouds that rose to about 4.5 km above the crater rim. Explosions on the following days of May generated ash clouds to heights of between 2 and 3.5 km. Low rumbling sounds on the 27th presumably accompanied other explosions. Only weak vapor vented at Crater 3 during May. Seismographs remained inoperative.

Information Contacts: B. Talai, D. Lolok, P. de Saint-Ours, and C. McKee, RVO.

June 1997 (BGVN 22:06) Cite this Report

June ash plumes to 2 km above summit

Mild Vulcanian activity prevailed at Crater 2 in late May and this continued in June. Except for 5-9 June, throughout the rest of the month Crater 2 emitted moderate, pale to dark- gray ash clouds. Some rose ~2.0 km above the summit. Fine ash fell on the N and NW parts of the volcano on the 10, 12 and 18 June. Occasional low rumbling noises were heard on 13, 15, 16, 19, 20, 22, 28, and 30 June. No glow was observed. As has been typical, Crater 3 remained quiet. Seismographs remained inoperative during June.

Information Contacts: Ben Talai, RVO.

July 1997 (BGVN 22:07) Cite this Report

Anomalous tilt precedes relatively forceful ash emissions

Although Crater 3 remained quiet and seismographs remained inoperative during July, moderate Vulcanian explosions continued at Crater 2. Throughout the month, Crater 2 produced gray ash clouds rising ~2 km above the summit. Fine ash fell on the N and NW parts of the volcano. On the night of 2 July observers saw incandescent lava projections; during 4-9 July there were weak explosions and roaring noises. Large explosions on 29 July produced dark gray ash clouds that rose ~5 km before drifting NW. Previously, on 22 March, aviators noted Langila ash clouds to 3-km altitude.

Information Contacts: B. Talai and H. Patia, RVO.

August 1997 (BGVN 22:08) Cite this Report

Gentle low-ash emissions from Crater 2

Throughout the month Crater 2 produced occasional gentle emissions of pale gray to brown ash clouds, generally low in ash content. There were single Vulcanian explosions on 3, 4, 14, and 19 August that were accompanied by forceful emissions of dark gray ash clouds that rose to ~3,000 m above the summit. Ash clouds were blown NW, producing light ashfalls at settlements 11 km from the volcano. Crater 3 remained quiet throughout August. There was no seismic recording during the month.

Information Contacts: Ben Talai, RVO.

September 1997 (BGVN 22:09) Cite this Report

A 2-km tall ash column produces local ashfalls on 14 September

At Crater 2, vapor and ash were emitted throughout the month. On the 14th an ash column rose to ~2 km and caused some local ash falls. No activity was reported from Crater 3. The seismographs were inoperative throughout the month.

Information Contacts: B. Talai and H. Patia, RVO.

October 1997 (BGVN 22:10) Cite this Report

Ash and vapor emissions from Crater 2

Crater 2 released white and blue vapors during 1-18 October; from 6 to 9 October the emissions were accompanied by weak rumbling noises. On 19 October, mild Vulcanian activity resumed at Crater 2, but Crater 3 remained quiet throughout the month. Emissions from Crater 2 during 19-31 October consisted of thin white to thick gray vapor and ash clouds that rose a few hundred meters above the crater rim; low rumbling noises were observed during the ash emissions.

A 25 October explosion produced a thick dark gray ash cloud that rose ~2,000 m above the summit and resulted in light ashfall NW of the volcano. Weak steady night glow was visible on 24 and 29 October.

Seismic recording resumed on 25 October; due to problems with the equipment, recording had not occurred since May 1996. Seismic activity was low during 25-31 October.

Information Contacts: B. Talai and H. Patia, RVO.

November 1997 (BGVN 22:11) Cite this Report

Increased eruptive activity at Crater 2

Since 20 October, increased activity was noticeable at Crater 2; emissions were thicker, occasional roaring or rumbling sounds were heard, and Vulcanian explosions produced dark black clouds that rose ~2 km above the crater. Occasional loud Vulcanian activity occurred throughout November. A bright fluctuating glow and occasional incandescent projections were visible during 15-25 November. Weak fumarolic vapor was released from Crater 3. Seismic levels remained moderate.

Information Contacts: Patrice de Saint-Ours, RVO.

December 1997 (BGVN 22:12) Cite this Report

Occasional explosions during December

Occasional explosions occurred during December at two of Langila's craters. Moderately thick gray ash was emitted from Crater 2 through most of the month, accompanied by deep roaring and rumbling sounds. An ashfall was reported on 5 December. Weak but steady and sometimes bright fluctuating night glows were visible on 4, 25, and 26 December. Crater 3 released weak fumarolic vapors. Neither seismograph was operational during December.

Information Contacts: Ben Talai, RVO.

January 1998 (BGVN 23:01) Cite this Report

Relatively quiet during January; occasional weak ash emission

Langila was relatively quiet throughout January. Crater 2 generally released weak to moderate emissions of white vapor, but on 10, 11, 17, 18, 20, and 21 January, weak pale-gray ash was emitted. Crater 3's activity consisted of gentle fumarolic emissions. Both craters were noiseless throughout the month and no glow was observed. The seismograph remained out of order.

Information Contacts: Ben Talai, RVO.

February 1998 (BGVN 23:02) Cite this Report

Intermittent eruptive activity at Crater 2

Throughout February, there was intermittent weak eruptive activity at Langila's Crater 2 while Crater 3 remained quiet. On the 3rd, two loud explosions were heard that produced thick dark ash clouds rising 2,500 m above the crater. A similar explosion occurred on 5 February. During 6-14 and 24-26 February, Crater 2 discharged small- to moderate-sized gray ash clouds. Low roaring and rumbling sounds were heard on the 20th, 22nd, and 24th. Crater 3 was restricted to weak fumarolic emissions the entire month. Both seismographs remained inoperative.

Information Contacts: Ben Talai, RVO.

April 1998 (BGVN 23:04) Cite this Report

Ash clouds rise up to 2.5 km during April

Moderately thick white vapor emissions continued at Crater 2 in April. Gray ash-laden clouds were seen rising to altitudes of 1-1.5 km on 7, 9-12, 16-17, and 22 April. On 25 April, ash clouds rose to an altitude of 2.5 km. A weak incandescent glow was seen on 22 and 28 April. Crater 3 released weak fumarolic vapors.

Information Contacts: Ben Talai, RVO.

July 1998 (BGVN 23:07) Cite this Report

Gas and ash emissions relatively quiet during May and June

Langila remained comparatively quiet during May and June. Direct radio communication to RVO had been a persistent problem, but reports were relayed by ships operating in the area.

Crater 2 continued weak-to-moderate emissions of white vapor during both months. During 9, 13, 17, and 19-21 May a blue vapor accompanied the usual white vapor. Occasional gray ash emissions were observed on 10 May, and 16, 22-24, 27, 29-30 June. Weak glow from the crater was seen on the nights of 2 and 3 May, and 16 and 29 June.

Crater 3 only released weak white fumarolic vapors. The seismograph remained non-operational during May and June.

Information Contacts: Ben Talai, RVO.

August 1998 (BGVN 23:08) Cite this Report

Weak vapor and ash emissions continue

During July, Crater 2 continued to release weak-to-moderate white vapor with occasional pale-gray ash. During 13-15 and 29 July the pale gray ash emissions changed to dark gray ash clouds that rose 2,000-2,500 m above the summit. Low roaring noises were heard 4-6, 8-9, and 16 July. No activity was reported from Crater 3 during July, and no glow was observed at either crater throughout the month.

During August both Crater 2 and 3 released low-to-moderate volumes of white vapor. There were also small amounts of blue vapor seen at Crater 2. One loud roaring and rumbling sound was heard at Crater 2 on 28 July accompanied by the emission of a dark-gray ash-laden cloud rising 1,000-2,000 m above the summit. This cloud was blown to the NW. The seismograph remained inoperative throughout July and August.

Information Contacts: Ben Talai, RVO.

October 1998 (BGVN 23:10) Cite this Report

Large explosion on 21 September causes ashfall

Crater 2 emitted thin to thick white vapor throughout September, with an occasional ash component. Weak roaring noises were reported on 1 September. One large explosion on 21 September sent ash to an altitude of 2-3 km and resulted in ashfalls to the SW. Crater 3 was quiet, emitting only thin white vapor.

The activity at Crater 2 during October was moderate and uneventful. Pale gray ash clouds rose intermittently to ~500 m, without sound. On 21 October, however, weak roaring and rumbling sounds accompanied emissions to 1,000-1,500 m and a bright fluctuating night glow.

Information Contacts: Patrice de Saint-Ours, Steve Saunders, and Ben Talai, RVO.

December 1998 (BGVN 23:12) Cite this Report

Ongoing Vulcanian eruption at Crater 2

The ongoing Vulcanian eruption at Crater 2 continued throughout November and December. Emissions consisted chiefly of gray ash clouds that drifted SW, resulting in fine ashfall. On 2 November a significant ash column was ejected forcefully up to ~2 km above the crater. Emissions during November were sometimes accompanied by roaring and rumbling sounds. No night glow was reported.

Information Contacts: Herman Patia, RVO.

January 1999 (BGVN 24:01) Cite this Report

Continuous white vapor with occasional ash emissions from Crater 2

Mild, intermittent, eruptive activity continued at Crater 2 in January, while Crater 3 remained quiet. Crater 2 emitted continuous white vapor with occasional mild emissions of pale gray to brown ash clouds. During 1-4 January most ash emissions were accompanied by low rumbling and roaring sounds. The emissions rose to about 500 m above the summit before blowing to the SE. There was no seismic recording during the month.

Information Contacts: Herman Patia, RVO.

April 1999 (BGVN 24:04) Cite this Report

Continued Vulcanian activity at Crater 2; Crater 3 is quiet

Crater 2 continued to display irregular Vulcanian eruptive activity and pale gray ash emissions. Crater 3 remained quiet. During March the ash plumes rose to 500-2,000 m above the summit before being blown NW. Variable winds in April caused the ash plumes to be blown to the NW, NE, and SE.

Information Contacts: Herman Patia, RVO.

June 1999 (BGVN 24:06) Cite this Report

Mild emissions with rare ash-bearing outbursts

Crater 2 exhibited mild, continuous volcanic activity during May and very low activity during June. The May activity primarily consisted of the escape of moderately thick gray to brown ash clouds. Weak rumbling and roaring noises occasionally accompanied the emissions and fairly significant ash columns were forcefully ejected to 2 km height on 4, 9, 11, and 30 May. The ash clouds drifted NW, resulting in downwind ashfall. The June activity was summarized as the escape of mostly small to moderate amounts of vapor. Occasional ash-bearing (gray-brown) ash clouds were seen. In both months, there was no visible night glow, Crater 3 remained quiet and only occasionally released thin white vapor. The seismograph remained inoperative.

Information Contacts: Ben Talai, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

October 1999 (BGVN 24:10) Cite this Report

Some strong ash emissions in September-October

No noise or night glow was reported from any vent during August and activity was very low in September and October. Throughout this period varying amounts of white vapor were observed from Craters 2 and 3. A blue component was observed in the vapors emitted from Crater 2 on the mornings of 4 and 5 August, whereas light to moderate ash emissions occurred on 6 and 7 August. On the morning of the 10th, ash was forcibly ejected 500-1,000 m above the crater rim. Only white vapor was emitted until the end of the month except on 25, 29, and 31 August when a light ash component was reported. On 21 and 30 September forceful emissions of thick brown ash were observed rising ~2 km above the summit from Crater 2. Such occasional forceful emissions continued into the first few days of October. The ash clouds rose 500-1,000 m above the summit and were later blown N. After that the emissions reduced to thin to thick white vapor.

Information Contacts: Ima Itikarai, Kila Mulina, and Steve Saunders, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

December 1999 (BGVN 24:12) Cite this Report

Intermittent eruptive activity; fine ashfall

Intermittent Vulcanian eruptive activity at Crater 2 continued throughout November. Crater 2 released small-to- moderate volumes of gray ash clouds on 2, 4, 9-17, 20, and 25-27 November. On the 25th, two explosions produced dense convoluted ash clouds that rose ~1.5 km above the crater, resulting in fine ashfall downwind to the SSE. A bright red glow was visible on the 15th. Crater 3 was quiet throughout the month. Visual observation reports in December were only received on the 1st and 2nd. On these two days the activity at both craters was low, producing very weak volumes of white vapor. The seismograph remained unoperational.

Information Contacts: I. Itikarai, H.Patia, and F. Taranu, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

March 2000 (BGVN 25:03) Cite this Report

Vapor and weak ash emissions in early 2000

Activity remained at a low level during 1-20 January and no unusual volcanism was reported for February or March. Reports were absent for 21-31 January, but earlier in the month Crater 2 released weak thin-to-thick white vapor in moderate volumes. On 3-6, 19, and 20 January the emissions included weak gray and brown ash clouds. Crater 3 released weak white vapor throughout the month. The seismograph remained non-operational.

Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano sits NE of the breached crater of Talawe. An extensive lava field reaches the coast on the north and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (Crater 3) was formed in 1960 and has a diameter of 150 m. The Cape Gloucester observation post, airstrip, and seismometer is 9 km N of the volcano.

Information Contacts: I. Itikarai, D. Lolok, K. Mulina, and F. Taranu, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

July 2000 (BGVN 25:07) Cite this Report

Forceful ash emissions on 5 and 9 April rise 1-2 km

This report covers April through June 2000. Activity remained at a low level in April. From visual observation reports received only up to 9 April, Crater 2 periodically gently released moderate to thick ash clouds. However, on 5 and 9 April, the ash clouds were released more forcefully and with rumbling sounds. These ash clouds rose 1-2 km above the summit before being blown SE. Crater 3 released light white vapor throughout the month.

Visual observations were next reported after 16 June. Crater 2 produced thick, white ash clouds in moderate volume. On 23 and 24 June, these clouds were accompanied by blue vapor. On 16 and 18 June, rumbling noises were heard. Crater 3 was inactive in June with the exception of a weak trail of thin white vapor escaping on 16 June.

The seismograph remained non-operational throughout the entire reporting period.

Information Contacts: I. Itikarai, D. Lolok, K. Mulina, and F. Taranu, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

November 2000 (BGVN 25:11) Cite this Report

Mild Vulcanian eruptions during July-October 2000

The mild Vulcanian eruptive activity that occurred at Langila's Crater 2 through June 2000 (BGVN 25:07) continued during July-October 2000. In addition, low-level volcanic activity continued at Crater 3. No reports of unusual activity were submitted during July and August.

During September, intermittent, mild Vulcanian activity occurred at Crater 2. The activity consisted of moderate emissions of thin-to-thick white vapor, which were occasionally accompanied by gray ash clouds. On 21, 25, and 30 September thick, dark gray, convoluting ash clouds were forcefully released, rose 200 m above the summit, blew to the N and NW, and deposited fine ash. On 7, 9-11, and 27 September wisps of blue vapor accompanied the emissions. During the month volcanic activity was low at Crater 3, with only thin white vapor sporadically visible.

Through October intermittent, mild Vulcanian eruptions continued at Crater 2. The vent usually emitted white vapor, which was sometimes accompanied by a blue tinge and occasionally by a light ash component. On 8 October a forceful emission of thick ash rose to 1 km above the crater rim. This heralded a few days of increased ash emissions, with some forcefully expelled light gray/brown clouds on the 15th. During 16-24 October continuous white vapor emissions with a small ash component were common. At 0801 on 24 October a dark gray-to-black ash column rose 1 km above the crater rim. On 25 October an ash cloud that rose to 2 km above the crater deposited ash toward the N. Likewise, at 0655 on 26 October a thick, white vapor plume was accompanied by an ash column that rose to 1 km above the crater rim. The ash emissions continued throughout the day, and similar activity occurred the next day. For the rest of the month activity was confined to white vapor with an occasional ash component. During October varying amounts of white fume were emitted from Crater 3. Throughout the period there were no reports of noises or night glow at the volcano; the seismograph remained out of operation.

Information Contacts: Ima Itikarai, David Lolok, Herman Patia, and Steve Saunders, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

January 2003 (BGVN 28:01) Cite this Report

Infrared data indicate activity during May-October 2002

Based on information from a pilot report, the Darwin Volcanic Ash Advisory Center (VAAC) reported that an ash cloud from Langila was observed on 11 July 2002 at about 0900 and rose to a height of ~3.4 km. No ash was identifiable on satellite imagery. This was the first reported activity since October 2000 (BGVN 25:11). RVO noted that the observatory at Langila was broken into in 2000 and had its radio stolen. There are no telephones nearby, and since then they have had to rely on mailed reports (very infrequent), reports from pilots, and the Darwin VAAC.

MODVOLC Thermal Alerts, 2001-2002. MODIS thermal alerts occurred on 25 May, 19 and 26 June, 12-15, 24, and 26 August, and 13 October 2002; there were no alerts in 2001. The largest number of alert pixels was 3 on 14 August. The highest alert ratio was -0.648 on 24 August. Putting these two together suggests the most intense activity in mid-late August, but this could be severely biased by cloudy days. Available maps do not allow an accurate location of the summit, and are not of a scale to provide accurate registration. However, all but one of the alert pixels are within ~1 km of each other so there appears to be a spatially restricted event consistent with a short flow (less than a few hundred meters long) or a small dome or incandescent vent a few tens of meters across, which would affect more than one pixel when the pixel boundary fell across, or very close to, the flow, dome, or vent. Both recently active craters (Crater 1 and Crater 2) are also within a 1-km area, along a NE-SW trend, similar to the orientation of the alert pixels.

Information Contacts: Diego Coppola and David A. Rothery, Department of Earth Sciences, The Open University, Milton Keynes, MK7 6AA, United Kingdom; Darwin VAAC, Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Steve Saunders, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

March 2003 (BGVN 28:03) Cite this Report

Large explosion on 18 January generates a dark ash column

The summit area was obscured by rain and clouds on many days in January and February. During clear days (4-5, 8-16, 18-21, and 25 January; 1-9 and 13-17 February), Crater 2 released weak to moderate emissions of white and white-gray vapor. Occasional ash-laden gray-brown and forceful dark gray emissions were produced on 10 and 14 January, respectively. The forceful emissions on the 14th were accompanied by low roaring noises. On 18 January a large explosion produced a thick dark ash column that penetrated the atmospheric clouds over the summit area. Occasional white-gray and gray-brown ash-laden emissions were observed on 1-6 February. On 3 and 4 February the same vent forcefully ejected dark gray ash clouds. Night glow was observed at Crater 2 on 14 and 15 January; some of the glow on the 15th changed into weak incandescent lava projections. Variable weak to bright red glow was observed at night on 3-6 and 14 February. On 3 February the glow fluctuated. Low rumbling noises were only heard on 6 February. Crater 3 released thin white vapor gently on 9-10, 12-13, and 19 January, and during 3-4, 6-9, 14, and 16 February. No emissions were observed on other clear days. There was no seismic recording.

Information Contacts: Ima Itikarai, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

February 2004 (BGVN 29:02) Cite this Report

MODIS thermal alerts in April 2003, and January 2004

Langila was last reported in BGVN 28:03, following a large ash-bearing explosion on 18 January 2003. MODIS thermal alerts were subsequently recorded on 9 April and 20, 23, 25, and 27 January 2004. One daylight alert was received and omitted (22 September 2003). Daylight alerts posted by the current algorithm are considered less reliable. No corroborative reports of activity have been received from the Rabaul Volcano Observatory or the Darwin Volcanic Ash Advisory Center (VAAC).

Information Contacts: Rob Wright, Luke Flynn, and Eric Pilger, MODIS Thermal Alert System, Hawaii Institute of Geophysics and Planetology (HIGP), School of Ocean and Earth Science and Technology, University of Hawaii at Manoa (URL: http://modis.hgip.hawaii.edu/).

June 2004 (BGVN 29:06) Cite this Report

Observed January 2004 lava ejections and four MODVOLC thermal alerts

Activity detected by MODVOLC at Langila was minimal, with only one alert pixel for 2003 (9 April) recorded just above the detection threshold, even though activity observed during January and February 2003 included weak lava projections (BGVN 28:03). Four alert pixels were recorded for 2004, on 20 (one each on Aqua and Terra), 25, and 27 January. All were 1-pixel alerts, with the highest alert ratio on 27 January at -0.764.

A thorough search of MODIS image data (i.e. original data, rather than the thresholded alert data on the MODVOLC website) was made for the period 20 May-25 October 2002, which revealed single-pixel sub-threshold thermal anomalies on Langila on a total of 25 dates, strengthening the case for the quasi-continuous or intermittent activity interpreted on the basis of MODVOLC alerts (BGVN 28:01).

Data acquisition and analysis. Reports from Diego Coppola and David A. Rothery provided analyses of MODIS thermal alerts during 2001 and 2002 (using the MODVOLC alert-detection algorithm) extracted from the MODIS Thermal Alerts website (http://modis.hgip.hawaii.edu/) maintained by the University of Hawaii HIGP MODIS Thermal Alerts team (BGVN 28:01). Rothery and Charlotte Saunders provided updates to 31 May 2004. MODVOLC data are now routinely available from the Aqua satellite (equator crossing times 0230 and 1430 local time) in addition to the original Terra satellite (equator crossing times 1030 and 2230 local time).

Information Contacts: David A. Rothery and Charlotte Saunders, Department of Earth Sciences, The Open University, Milton Keynes, MK7 6AA, United Kingdom.

May 2005 (BGVN 30:05) Cite this Report

Ash emissions and lava flow during April-June 2005

Langila was last reported on in BGVN 29:06, as part of a MODIS data summary, although the last prominent event there was on 18 January 2003, when a large explosion produced a thick dark ash column that penetrated the weather clouds over the summit area (BGVN 28:03).

A plume from Langila was visible on satellite imagery on 17 December 2004 according to the Darwin VAAC. The plume reached an unknown height and extended NW.

Between 28 April 2005 and 4 May 2005 the Rabaul Volcano Observatory (RVO) received reports of activity at Langila characterized by forceful emissions of thick white to gray ash-laden clouds rising ~ 700-800 m above the summit crater. Occasional continuous rumbling and explosive noises were heard and incandescence was visible at night. During early May, incandescent lava fragments were ejected. Activity increased at about 1300 on 4 May 2005, when white-to-gray ash emissions changed to dark ash clouds. Explosions became frequent, with incandescent lava fragments ejected again, and very bright glow was visible during the night. Around 1200 on 5 May 2005 the color of the ash emissions changed from dark gray to white-to-gray. A lava flow was produced but no further detail is available. Based on information from RVO, the Darwin VAAC reported that ash emissions from Langila rose to ~ 2.1 km altitude on 3 May. A very small plume and a hot spot were visible on satellite imagery. Ash clouds from the eruption were blown generally NW towards Kilenge ~ 100 km away, where light to moderate ashfall was reported.

According to the Darwin VAAC, low-level ash plumes emitted from Langila were visible on satellite imagery during 8-13 June 2005. RVO reported to the Darwin VAAC that moderate eruptive activity was expected to continue.

The International Federation of Red Cross and Red Crescent Societies (IFRC) reported that eruptive activity occurred at Langila on 2 June with more ash than normal being emitted from the volcano. Prevailing winds carried most of the initial ashfall to the sea, but lower-level winds redirected the ash back onto the island. About 10,000 people live near the volcano, and there were reports of increased cases of respiratory problems and eye irritation. During an aerial inspection of the area on 6 June 2005, IFRC determined that ~ 3,490 people had been affected by the eruption, mainly in the villages of Aitavala, Masele, Kilenge, Ongaea, Potne, and Sumel, but also to a lesser extent in Vem, Galegale, Tauale, and Laut. Ashfall damaged small food gardens and contaminated some water sources. The provincial government encouraged voluntary evacuation of affected areas.

During 16-17 June 2005, ash plumes from Langila were visible on satellite imagery (figure 4). The heights of the plumes were not reported.

Figure 4. On 21 June 2005 the Moderate Resolution Imaging Spectroradiometer (MODIS), flying on NASA's Aqua satellite, captured this image of Langila, Ulawun, and Rabaul. At the time MODIS captured this image, Langila showed the biggest plume of volcanic ash, followed by Ulawun. In all cases, winds pushed the ash clouds NW over the ocean. NASA image courtesy Jesse Allen, based on data from the MODIS Rapid Response Team at NASA.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea; International Federation of Red Cross And Red Crescent Societies (IFRC), Langila Volcano Information Bulletin No. 1 (URL: https://reliefweb.int/).

August 2005 (BGVN 30:08) Cite this Report

Increased eruptive vigor leads to ashfall damage in mid-2005

The Darwin VAAC issued an activity report stating that the Rabaul Volcano Observatory (RVO) had noted elevated activity since 24 April 2005. Between 28 April 2005 and 4 May 2005 Langila emitted more ash than normal, and the International Federation of Red Cross And Red Crescent Societies (IFRC) determined that ~ 3,490 people had been affected by the eruption when ashfall damaged small food gardens and contaminated some water sources.

VAAC reports on 4 May and 6-7 May noted thin plumes extending NW 110 km and 75 km, respectively. Later, on 7-8 May, the identifiable plume was half as long and diminishing. Plumes and other diagnostics eventually became obscured by weather clouds. On 8 June analysts at the Darwin VAAC saw a low-altitude plume and a hot spot. The plume moved westward and remained visible into 9 June when it ceased being detectible.

During 13-19 June 2005, Langila's Crater 2 continued to erupt. At times the eruption was marked by moderate to strong emissions of thick gray-brown ash clouds occurring at irregular intervals. Ash clouds from the eruption rose variably to 700-1000 m before they were blown to the W and NW. At other times weak to moderate emissions of light gray ash clouds were observed. Considerable ash fell near the volcano and extended to the W and NW, between Warimo and Aimola. Crater 3 was quiet. Low and high frequency earthquakes and volcanic tremor were recorded.

The Darwin VAAC reported a Langila plume on 13 June to 3-4 km altitude, but cloud cover later obscured the plume. Another plume became visible on imagery on 16 June moving W at 30 km/hour at an estimated altitude of ~ 3 km; ongoing plumes became hard to see about mid-day on 17 June. Several other episodes of plume image detection were seen. One was identified by the VAAC on 21 June, with an observation of altitude to ~ 3 km and plume length reaching 300 km to the NW. The evidence of eruption only continued until the next day, when cloud cover obscured the area. A further, brief episode of plume detection occurred beginning early on 25 June but detection ended before noon. On 30 June, the Darwin VAAC repeated a US Air Force Weather Agency (AFWA) report on a Langila plume seen on imagery, blowing SW at 20 km/hr and reaching ~ 3 km altitude. By about 6 hours later that plume ceased to be visible.

Moderate levels of volcanic activity occurred at Langila's Crater 2 during 15-21 August. The activity was marked by occasional sub-continuous forceful emissions of ash clouds. The ash clouds rose as high as 1 km before drifting N and NW. Fine ash fell in villages along the coast. On the evening of 18 August projections of incandescent lava fragments were seen. Based on a pilot report, the Darwin VAAC reported that ash from Langila was visible in the vicinity of the volcano on 23 August, at 3-4.6 km altitude. A plume was seen a bit later on MODIS imagery extending 110 km to the NNW but ash was not visible in satellite imagery.

Information Contacts: Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea; International Federation of Red Cross And Red Crescent Societies (IFRC) (URL: https://reliefweb.int/); U.S. Air Force Weather Agency (AFWA)/XOGM, Offutt Air Force Base, NE 68113, USA; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/).

November 2005 (BGVN 30:11) Cite this Report

Active during August-September, decreasing during October-November

Rabaul Volcano Observatory (RVO) reported that during 22-28 August 2005, modest eruptive activity was observed at Langila's Crater 2. Occasional forceful emissions of ash produced plumes that rose ~ 1 km above the crater on 22 and 25 August, but reached only several hundred meters after that. The ash plumes drifted N and NW, resulting in fine ashfall in downwind areas, including the town of Kilenge. Seismicity was at low levels, consisting mainly of low-frequency earthquakes. The Darwin Volcanic Ash Advisory Centre (VAAC) reported that a plume was visible on satellite imagery on 30 August extending NNW.

During 12-18 September, Crater 2 continued to forcefully erupt ash at irregular intervals. The resultant ash plumes drifted NW and W. Incandescence and weak projections of volcanic material were visible on the evening of 13 September. There was no activity at Crater 3. Seismicity was at low levels at the volcano, consisting mainly of low-frequency earthquakes.

During 20-23 October, low-level plumes from Langila were occasionally visible on satellite imagery. On 29 October, a plume from Langila was visible on satellite imagery at an altitude of ~ 2.7 km.

During 11-12 November, low-level ash plumes emitted from Langila were visible. The heights of the plumes were not reported.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac); Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea; International Federation of Red Cross And Red Crescent Societies (IFRC) (URL: https://reliefweb.int/).

February 2006 (BGVN 31:02) Cite this Report

Crater 2 continues activity in November 2005-January 2006

Vulcanian eruptions continued at Langila's Crater 2 during 21-27 November 2005, with a slight increase in the level of activity compared to the previous week. The increase in activity was marked by light to dark gray ash emissions that sometimes rose to heights between 1 and 2 km above the summit crater (7,650-10,900 feet altitude). The ash clouds drifted W, SW, SE, and NW, depositing ash in those areas. Incandescence and projections of volcanic material were visible at the volcano during the nights of 21, 23, and 25-27 November along with weak to loud noises. Crater 3 was quiet during the report period. Seismicity was at low-to-moderate levels, consisting of low-frequency earthquakes associated with the Vulcanian activity and periodic volcanic tremor.

A slight increase in vulcanian activity occurred at Langila's Crater 2 during 1-15 January. The increase was characterized by nearly continuous ash emissions that rose to 1-2 km above the summit (7,650-10,900 feet altitude) and drifted WSW. Occasionally during the report period observers noted loud noises, incandescence, and weak emissions of glowing lava fragments. Crater 3 continued to be quiet during this period.

Information Contacts: Ima Itikarai, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea; Andrew Tupper, Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/).

May 2006 (BGVN 31:05) Cite this Report

Moderate activity steady through March 2006

Moderate activity took place at Langila during January 2006, including continuous ash fall, rumbling, and weak emissions of lava fragments. During 20 January to 7 February eruptive activity was characterized by thin, pale gray ash clouds. Minimal noises were heard on 26-27 February. A changing weak-to-bright glow accompanied by projections of glowing lava fragments were visible on the nights of 22-23 and 28 February, and 1-2, and 6 March. Moderate-to-thick dark gray ash clouds were reported on 1-2, 6-7, and 9 March. Ash plumes rose less than 2 km above the summit crater before drifting SW-W of the volcano. Crater 3 remained quiet.

Information Contacts: Ima Itikarai and Herman Patia, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.

February 2007 (BGVN 32:02) Cite this Report

Emission of ash plumes continues through March 2007

Moderate activity occurred at Langila between January and March 2006 (BGVN 31:05), with eruptive activity accompanied by a continuous ashfall, rumbling, and weak emissions of lava fragments. Since March 2006, activity has continued at Crater 2.

According to the Darwin Volcanic Ash Advisory Center (VAAC), eruptions at Crater 2 occurred in August 2006 and from October 2006 through March 2007, with explosions of incandescent lava fragments, roaring noises at regular intervals, and continuous emissions of gray-to-brown ash plumes. Plumes generally reached 2.3-3.3 km altitude, although on 31 October a small ash plume rose to an altitude of 4.6 km. Ash plumes were occasionally visible on satellite imagery. During October and through the first part of January 2007, plumes generally drifted N, NW, W, WNW, and NE; between the end of January and March, plumes drifted SE and SW.

Thermal anomalies detected by MODIS instruments on the Terra and Aqua satellites were absent after 2 January 2006 until 21 July 2006. The same system (the HIGP Thermal Alerts System) identified anomalies again on 24 and 31 October, 12 and 21 November, 16 and 27 December 2006, 6 January, 8 March, and 18 March 2007.

Information Contacts: Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).

February 2008 (BGVN 33:02) Cite this Report

Intermittent ash emissions in May and August 2007

Satellite thermal anomalies occurred at or near Langila on three different days in early 2007 (BGVN 32:02). Although erupting regularly, only one other anomaly (on 2 April 2007) was detected after that time through 6 March 2008. Langila is noted for its ongoing fluctuating eruptions and occasional ash clouds that rise to more than 5 km altitude and pose a threat to aviation. Throughout this reporting period, April 2007 to January 2008, ash emissions were usually accompanied by weak to moderately loud roaring.

During May 2007, the Rabaul Volcanic Observatory (RVO) reported the emission of ash clouds from Langila's Crater 2. Ash plumes rose to an altitude of 3.3-4.3 km and drifted NW. Weak roaring noises were heard on 11-12 May and a weak glow was visible on 7-8, 11-12, and 15 May. Weak roaring noises were again heard on 20 May, and an increased phase of eruptive activity that began on 22 May continued until end of the month. The increased activity was characterized by forceful emission of thick pale-gray to dark gray-brown ash clouds from 22-27 May. The emission changed to subcontinuous thick dark gray-brown ash clouds on 28-29 May before changing back to occasional thick, pale-gray clouds on 30-31 May. Two large explosions on 30 May accompanied the ash emission. The ash clouds from these two explosions rose 4 km above the summit before being blown NW. On the other days, the ash clouds rose 2-3 km above the summit before drifting NW of the volcano. Continuous fine ashfall occurred at Kilenge Catholic Mission (~10 km NW) and surrounding areas during 22-31 May. The ash emissions were accompanied by occasional weak to loud roaring noises from the 22 to 28 May before turning subcontinuous during 29-31 May. On 30 May two large explosions produced ash plumes that rose to ~5.3 km and drifted NW. A weak glow was visible on 7-8, 11-12, 15, and 20 May and again on 29 and 31 May. Incandescence was visible on 29 May. On 26 May, the seismograph deployed at Kilenge became operational.

During June RVO reported a slight decrease in eruptive activity that began on 22 May, however, the emissions of ash plumes from Crater 2 were occasionally forceful. The emissions were continuous on 6, 7, and 10 June and accompanied by roaring noises; booming noises were heard on 1 and 10 June. Ash plumes rose to ~ 2.3-4.3 km and drifted NNW. Based on observations of satellite imagery and information from RVO, the Darwin VAAC reported that on 3 June, an ash plume rose to an altitude of 3 km and drifted W. Ashfall was again reported at Kilenge Catholic Mission and surrounding areas. Seismic activity in June was at a high level, dominated by continuous tremor and occasional explosion signals. During the latter part of the month, seismic activity decreased to a low-moderate level. It was dominated by continuous irregular tremors and occasional harmonic tremors. Low-frequency earthquakes ranged from 1 to 7 events per day.

During July 2007, eruptive activity continued at a low level but included thin-to-thick, pale-gray ash clouds. Weak roaring noises were heard on 1 July, but glow was absent at night. On 2 July ash clouds were ejected forcefully and rose ~2 km, drifted NW, and resulted in a fine ashfall downwind. On 6-7, and 9-13 July, ash clouds rose less than 1 km above the summit before drifting NNW. Except for 1 July when weak roaring noises were heard, the volcano was quiet and without appreciable night glow. Seismicity registered at low-moderate levels, dominated by non-harmonic and harmonic tremor of continuous, irregular, or banded character. During July, the daily number of low-frequency earthquakes ranged between 1 and 12 events per day. The one high-frequency earthquake occurred on 27 July.

RVO reports noted mild but continuous ash and white vapor plumes from Crater 2 during 1 August-30 September. Ash plumes generally rose to altitudes of ~1.8-3.3 km and drifted WNW. On 8 August, a large explosion produced an ash plume that rose to an altitude of 5.3 km and drifted SW. Ashfall was reported downwind. Incandescent fragments were ejected from the summit on 21-22 September.

During 1-7 October 2007, RVO reported low-to-moderate eruptive activity consisting of continuous emission of pale gray ash clouds which rose to ~1.8-3.3 km and were blown W to NW. During the second week, the white vapor accompanied by pale gray ash clouds continued; these rose less than 1 km before being blown to the NW of the volcano. On 19, 16, and 27 October, the ash clouds rose less than 2 km before being blown WNW. Consistently, the ash emissions were accompanied by occasional weak-to-loud roaring or booming noises. On most occasions, there was no glow observed at night, however, a weak-to-bright glow accompanied by projection of incandescent lava fragments was visible on 12 and 22 October. Crater 3 remained quiet. Seismic activity was at low-to- moderate level dominated by low frequency earthquakes and bands of harmonic and non-harmonic tremors. The daily number of low-frequency earthquakes ranged from 2-15. Less than 10 high-frequency events were recorded during October.

In January 2008, activity generally remained low. Some ash fell on 6-7, and 9 January with fluctuating glow visible. On 10, 13, and 25 January the incandescent glow was bright. More direct observations through late February 2008 by RVO staff and affiliates confirmed ongoing eruptions. During February, Crater 2 continued to erupt. Most days, these eruptions generated ash plumes typically rising a few hundred meters. Observers noted incandescent glow or noises on 7, 9, 11, and 21-23 February.

Information Contacts: Herman Patia, Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, Northern Territory 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).

November 2009 (BGVN 34:11) Cite this Report

Strong ash explosions during 20-24 September 2009

Although the Rabaul Volcano Observatory (RVO) reported ash eruptions and glow as late as 23 February 2008 (BGVN 33:02), subsequent available reports did not include Langila until July 2008. That report noted weak emissions of light gray ash clouds during 1-6 July, followed by white vapor for the remainder of the month, with no glow observed. Activity at Langila was again not described in available observatory reports until September 2009, and thermal anomalies were noted in early October 2009.

Vulcanian activity occurred from Crater 2 throughout September and the first week of October. From the beginning of September emissions consisted of light brown to dense pale white/gray ash clouds that rose 800-1,000 m above the crater rim. Occasional roaring and rumbling noises were heard. This eruptive episode produced significant amounts of ash, primarily affecting areas NW, W, and SW of the volcano.

Stronger activity during 20-24 September consisted of dense dark gray ash clouds and some incandescent ejections. Plumes rose 2,000-3,000 m above the rim during this period. The emissions also produced continuous roaring noises and booming explosion sounds. Some lightning discharges accompanied the explosions. GNS of New Zealand and the Darwin VAAC detected very strong airborne sulfur dioxide (SO₂) in satellite data on 26 September. On-site observations did not indicate strong activity that day, so it was thought to have been from the 20-24 September activity.

Emissions subsided on 25 September to the previous level, and continued during the first week of October, then declined to continuous white-gray ash clouds. This type of activity, with plume heights around 600 m, continued with minor variations until the end of October. The audible noises declined to occasional weak roaring after the first week of October. Night-time glow was also visible throughout September and October.

Some plumes during this episode extended great distances downwind, prompting aviation warnings. Based on analyses of satellite imagery, the Darwin VAAC reported that on 12 September an ash plume rose to an altitude of 3 km and drifted 35 km W. On 29 September ash plumes rose to altitudes of 2.4-4.3 km and drifted 75-220 km NW. Another ash plume the next day drifted 260 km NW at an altitude of 4.3 km. A diffuse ash plume on 5 October rose to an altitude of 3 km and drifted 185 km N.

Thermal anomalies identified in MODIS data were recorded on 10, 22, and 26 September, and 5-6 October. MODVOLC alert pixels appeared to be located outside of the crater on the ENE slope.

Information Contacts: Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).

February 2010 (BGVN 35:02) Cite this Report

Weak ash plumes in February 2010

In September 2009 eruptions occurred at Langila's Crater 2, sending aloft dense ash plumes seen for hundreds of kilometers. Activity subsided but continued as late as the end of October 2009 (BGVN 34:11). Later reports from the Rabaul Volcano Observatory noted activity at Langila in December 2009 and February 2010. No MODVOC thermal alerts were recorded after 5-6 October 2009, through February 2010.

Vulcanian eruptive activity continued at Crater 2 throughout December 2009. The eruptive activity consisted of variable gray ash clouds on most days of the month that rose ~ 1 km above the summit before being blown NE, causing fine ashfall downwind.

During 11-15 February 2010 observers saw weak ash plumes from Crater 2. During the latter part of the month the plumes were stronger, rising 700-900 m above the crater and drifting SE and SW. During 15-19 February observers heard occasional weak booming noises.

Information Contacts: Ima Itikarai, Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).

January 2016 (BGVN 41:01) Cite this Report

Ash plumes rise to an altitude of 1.5-2.1 km in December 2012

After an eruption in September 2009, activity at Langila subsided, yet still remained above normal through at least February 2010, with ash plumes rising about 1 km or less above the summit (BGVN 35:02). No additional activity was reported until 1 December 2012, when, according to the Darwin Volcanic Ash Advisory Centre (VAAC), a pilot observed an ash plume at an altitude of 1.5 km. Ash was not detected in satellite imagery. The Darwin VAAC reported that another ash plume was seen in MTSAT-2 visible imagery on 5 December that rose to an altitude of 2.1 km and drifted 110 km NW. Elevated sulfur dioxide concentrations were also detected in OMI (Ozone Monitoring Instrument) satellite data.

Few thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were identified during the reporting period (March 2010-December 2012). Weak thermal anomalies were reported 24 July 2010 and 21 July 2012, but they were well down the NE flank, and not likely related to volcanism. One of two 28 July 2011 weak anomalies were located close to the crater, but the other was further NE. Seven stronger anomalies were detected in December 2012 on the 9th (1 pixel), 11th (1), 18th (1), 23rd (3), and 25th (1); the pixels identified during 9-23 December were close to the active crater.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/).

January 2017 (BGVN 42:01) Cite this Report

Weak ash plumes during April-May and November-December 2016

After two explosions at Langila produced ash plumes that rose to 1.5 and 2.1 km in early December 2012 (BGVN 41.01), no further information about the volcano's activity was available from the Rabaul Volcano Observatory or the Darwin VAAC until April 2016. This report discusses two new eruptions in 2016, one during 2 April-13 May and the other during 3 November-24 December. Observations of ash plumes continued into mid-January 2017.

Thermal anomalies, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were occasionally detected after 2012. During 2013, seven anomalies were reported during 23 October-1 December (4 pixels on 25 October); during 2014-2015, a possible anomaly was identified on 23 August 2014 NE of the crater and thus probably not associated with volcanic activity.

During 2016, the Darwin VAAC reported the ejection of several ash plumes during 2 April-13 May and 3 November-24 December (table 3). Most plumes rose between 2-3.3 km in altitude. MODVOLC thermal alerts were also seen during those two periods, with six anomalies during April and May, and one reported in November During 20-27 December 2016, five thermal anomalies were reported (most with more than one pixel). Two alert pixels in August were weak and somewhat E of the volcano, and probably not associated with activity.

Table 3. Ash plumes from Langila reported during April-May and November-December 2016. Observations are based on analyses of satellite imagery, ground observations by the Rabaul Volcano Observatory, and wind data; dates are based on local time. Courtesy of the Darwin VAAC.

The Mirova (Middle InfraRed Observation of Volcanic Activity) volcano hotspot detection system, also based on analysis of MODIS data, also detected occasional hotspots during 2016 (figure 5). Most occurred during April-May and November-December, but a few intermittent anomalies were noted every month during June-October as well. The heat radiated by the volcanic activity (or Volcanic Radiative Power, as measured in watts) was mostly less than 0.5 W.

Figure 5. Plot of MIROVA thermal anomaly MODIS data during 7 January 2016-6 January 2017. Periods of more frequent anomalies in April-May and November-December 2016 correspond to reports of ash plumes. Courtesy of MIROVA.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Rabaul Volcano Observatory (RVO), PO Box 386, Rabaul, Papua New Guinea; Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/, http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).

September 2017 (BGVN 42:09) Cite this Report

Eruption continues, intensifying from mid-December 2016 through July 2017

Eruptive activity at Langila was intermittent during 2016, with ash plumes seen during April-May and November-December (BGVN 42:01); thermal anomalies were somewhat more commonly detected, but were also intermittent. No reports were available from the Rabaul Volcano Observatory during January-July 2017, but volcanic ash warnings were issued by the Darwin Volcanic Ash Advisory Centre (VAAC). Thermal anomaly data acquired by satellite-based MODIS instruments showed a strong increase in activity beginning in mid-December 2016 that was ongoing as of early August 2017.

Ash plumes were reported frequently during the first half of 2017 except during March and early April. The plumes rose to altitudes between 1.8 and 3 km (table 4). The aviation color code has remained at Orange (third highest of a four-step universal volcanic ash alert level system for aviation) throughout 2016 and through July 2017.

Table 4. Ash plumes from Langila reported during January-June 2017. Observations are based on analyses of satellite imagery and wind data; dates are based on local time. Courtesy of the Darwin VAAC.

Thermal alerts, based on MODIS satellite instruments analyzed using the MODVOLC algorithm, were identified often during December 2016 through June 2017. The MIROVA volcano hotspot detection system, also based on analysis of MODIS data, detected occasional anomalies from August 2016 through late December 2016 (BGVN 42:01), followed by more continuous anomalies through late July 2017 (figure 6). The most intense anomalies over this time period occurred from mid-April to early May 2017.

Figure 6. Plot of MIROVA thermal anomaly MODIS data for the year ending on 8 August 2017. Courtesy of MIROVA.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).

June 2018 (BGVN 43:06) Cite this Report

Gradual decline in activity after July 2017, but continuing through May 2018

Langila, one of the most active volcanoes of New Britain (figure 7), has been intermittently ejecting ash since April 2016 (BGVN 42:09). Volcanic ash warnings continue to be issued by the Darwin Volcanic Ash Advisory Centre (VAAC). Recent ash plume altitudes (table 5) are in the range of 1.5-2.5 km, but several in mid-April to mid-May 2018 reached up to twice that level. Thermal anomaly data acquired by satellite-based MODIS instruments showed a gradual decrease in power level and occurrence through mid- to late-2017, followed by significantly fewer alerts and anomalies in the first half of 2018. Rabaul Volcano Observatory (RVO) data indicates the activity during 2017 was primarily located in Crater 2 (northern-most crater).

Figure 7. Satellite imagery showing Langila volcano at the far NW end of New Britain island. The brown color of recent lava flows and other volcanic deposits are easily noticeable compared to green vegetated areas. The volcano is about 9 km due south of the community labeled Poini. Imagery in this view is from sources listed on the image; courtesy of Google Earth.

Table 5. Reported data by Darwin Volcanic Ash Advisory Centre (VAAC) on ash plume altitude and drift from Langila based on analyses of satellite imagery and wind model data between 21 June 2017 and 28 May 2018.

MIROVA analysis of thermal anomalies measured by MODIS satellite sensors show a gradual decline of radiative power from early June 2017 to the end of the year (figure 8). Sporadic low-power anomalies occurred in January, April, and May 2018.

Figure 8. Thermal anomalies from MODIS data analyzed by MIROVA, plotted as log radiative power vs time for the year ending 6 June 2018. Courtesy of MIROVA.

Thermal alerts from MODVOLC analyses were concentrated between early June 2017 and late September 2017 (figure 9), with only one pixel being measured in 2018 through early June, that alert being on 5 January 2018.

Figure 9. Map showing thermal anomalies from MODIS data analyzed by MODVOLC for the year ending 6 June 2018. Courtesy of HIGP - MODVOLC Thermal Alerts System.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Rabaul Volcano Observatory (RVO), Geohazards Management Division, Department of Mineral Policy and Geohazards Management (DMPGM), PO Box 3386, Kokopo, East New Britain Province, Papua New Guinea.

November 2018 (BGVN 43:11) Cite this Report

Several weak ash plumes during June, September, and October 2018

After Vulcanian activity in the latter part of 2009, activity at Langila subsided, with infrequent activity until 2016, when activity increased somewhat through May 2018 (BGVN 34:11, 35:02, 42:01, and 42:09). This pattern of intermittent activity continued through October 2018. No reports were available from the Rabaul Volcano Observatory during the current reporting period (June-October 2018), but volcanic ash warnings were issued by the Darwin Volcanic Ash Advisory Centre (VAAC).

Four explosions were reported by the Darwin VAAC in June 2018, generating ash plumes that rose 2.1-3.4 km (table 6). There were no reports of an explosion in July or August 2018. Additional ash plumes were detected on 29 September and 30 October 2018

Table 6. Reports of ash plumes from Langila during 1 June-30 October 2018 based on analyses of satellite imagery and wind model data. Courtesy of the Darwin VAAC.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL:http://www.bom.gov.au/info/vaac/).

November 2020 (BGVN 45:11) Cite this Report

Intermittent ash emissions and thermal anomalies through October 2020

Frequent mild-to-moderate explosive eruptions with ash emissions and lava flows have been recorded since the 19th century from three active craters at the summit of Langila, which is a group of four small overlapping composite basaltic-andesitic cones at the western tip of Papua New Guinea’s New Britain Island (figure 10). The remoteness of its location makes ground-based observations rare from the Rabaul Volcano Observatory (RVO) staff or visitors, and thus most information comes from satellite sources and the Darwin Volcanic Ash Advisory Center (VAAC). Satellite thermal images and MODIS thermal data suggest possible eruptions not previously reported during 2011, 2012, and 2013. A substantial eruption likely began in late 2015 that included thermal anomalies, ash emissions, and extensive lava flows, lasting at least through 2018. Intermittent thermal anomalies and explosive activity since 2018 suggest continued activity through October 2020. This report reviews satellite visual and thermal information about activity during 2011-2018 and provides details of activity from November 2018-October 2020.

Figure 10. A monthly composite satellite image from June 2020 shows the summit craters of Langila. They closely resemble the sketch of the summit created in 1970 (SEAN 03:05), indicating little change in the summit morphology over the last 50 years. The summit of the adjacent Mount Talawe is about 450 m higher than the highest point of Langila at the crater rim around Chimney Crater. Chimney Crater (No. 1) is about 300 m across. Courtesy of Planet Labs, Inc.

Summary of activity during 2011-2020. Primary data sources for Langila since 2011 have been MODIS thermal data in the form of MODVOLC thermal alerts and MIROVA graphs (since 2016), the Darwin Volcanic Ash Advisory Center, and satellite images from both LANDSAT-8 (August 2013-October 2015) and Sentinel-2 (since October 2015). Based on information from those sources (figure 11), volcanic activity may have occurred on 28 July 2011, 21 July 2012, and during 23 October-1 December 2013. A confirmed eruption from 1-5 December 2012 was previously reported (BGVN 41:01). Increased thermal activity late in 2015 was followed by multiple ash emissions during 2016 (BGVN 42:01); strong evidence of a significant eruption with extensive lava flows is preserved in satellite imagery and heat flow graphs throughout 2017 (BGVN 42:09, 43:06) and ash emissions were frequent during 2018 (BGVN 43:11). Although activity decreased significantly during 2019 and 2020, satellite-based evidence of low-level thermal activity continued. Ash emissions were reported again during August-October 2020.

Figure 11. A summary table indicating observations of possible volcanic activity at Langila from multiple sources during January 2011-October 2020. Each month with data indicating possible volcanism is highlighted in a specific color for that source. MODVOLC (yellow) is the Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System. DVAAC (green) is the Darwin Volcanic Ash Advisory Center. LANDSAT-8 (blue) is the USGS-run satellite launched in 2013 that houses two instruments, the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). Sentinel-2 (red) is a satellite system launched by the European Space Agency (ESA) in 2015 that monitors variability in land surface conditions. MIROVA (purple) is a Near Real Time Volcanic HotSpot Detection System run by the Universities of Turin and Florence (Italy) based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data.

Possible eruptions during 2011-2013. Limited MODVOLC thermal alert and Landsat 8 data suggest possible eruptions not previously recorded for Langila on 28 July 2011, 21 July 2012, and during 23 October-1 December 2013. An eruption that produced ash emissions and MODVOLC thermal anomalies during December 2012 was previously reported (BGVN 41:01). The two MODVOLC thermal alerts from 28 July 2011 are located NE of the crater complex near the summit in a region with recent lava flow activity. The four MODVOLC alerts from 21 July 2012 are also located NE of the craters but are a few kilometers farther away and may be the result of fires. Seven MODVOLC alerts were recorded during 9-25 December 2012 following ash emissions reported earlier in the month. A group of twelve MODVOLC alerts that occurred between 23 October and 1 December 2013 are also located on the NE side of the crater complex in the same area as anomalies following the December 2012 eruption (figure 12). Thermal anomalies were present at the craters in 2 and 18 December 2013 Landsat thermal images, shortly after the 23 October-1 December MODVOLC alerts that suggested eruptive activity.

Figure 12. MODVOLC alerts show thermal anomalies and possible eruptive activity at Langila during 2011-2013. Top left: 28 July 2011. Top right: 21 July 2012 (possibly from a fire). Bottom left: 9-25 December 2012 after observed ash emissions during 1-5 December 2012. Bottom right: Twelve alerts were recorded between 23 October and 1 December 2013 in the same area as the alerts from December 2012. Courtesy of HIGP MODVOLC Thermal Alerts System.

Observations during 2014-2015. Landsat 8 imagery from 2014 and 2015 show intermittent thermal anomalies from the summit area. A steam plume drifted N and a weak thermal anomaly was present at the summit craters on 11 May 2014. On 30 July, the anomaly at the crater was small but distinct, and a steam plume drifted NW from the crater. Thermal anomalies were present again at the summit craters on 18 October and 3 November, but no longer seen by 19 November 2014. Plumes of steam drifted NW from Crater 2 on 23 February and 28 April 2015, and weak thermal anomalies were present inside the crater on those days.

Eruption during late 2015-2018. Previous reports have discussed VAAC, MODVOLC, and MIROVA data with respect to activity during 2016-2018 (BGVN 42:01, 42:09, 43:06, and 43:11), but satellite imagery and photographs presented here provide additional details. Landsat images from 5 and 21 October 2015 show thermal anomalies at the craters. Both the Landsat 8 image on 21 October and the first Sentinel-2 image on 22 October show probable volcanic and non-volcanic activity. A thermal anomaly was detected inside the summit crater, and anomalies and smoke, likely from fires burning in the forest, were also present on the E flank. The summit thermal anomaly persisted in the 24 November 2015 Sentinel-2 image. Two distinct hotspots appeared inside Crater 2 in Sentinel 2 satellite imagery on 10 January 2016 along with a dense plume of steam that drifted NW, but there were no thermal anomalies apparent in the same view on 9 February 2016. A previously reported period of increased activity began in March 2016; ash emissions were reported for the first time since December 2012 in April 2016 (BGVN 42:01). Such emissions occurred again in May, November, and December. In addition to the 10 January 2016 thermal anomalies, anomalies and steam plumes at the summit appeared in satellite imagery on 22 April, 11 and 18 July, 27 August, 19 and 29 October, and 25 November 2016 (figure 13). An ash emission was seen in the 5 December Sentinel-2 image. A significant increase in thermal energy was recorded by the MIROVA project beginning in late December 2016 (BGVN 42:01).

Figure 13. Multiple thermal anomalies during late 2015 and 2016 suggested eruptive activity. Top left: a single anomaly was present inside the summit crater of Langila in Sentinel-2 imagery on 22 October 2015; other anomalies on the E flank were likely due to fires. Top right and bottom left: Two hotspots were visible inside Crater 2 on 10 January and 27 August 2016. Bottom right: A single larger anomaly with a dense steam plume was present on 25 November 2016. Atmospheric penetration (bands 12, 11, 8a) rendering courtesy of Sentinel Hub Playground.

Significant lava flow activity was recorded in satellite images during January-October 2017, along with MIROVA data indicating high levels of heat flow (BGVNN 43:06). In addition to two anomalies at the summit on 27 January 2017, a lava flow about 1 km long trended NW on the W flank at the edge of a larger flow field. By 8 March large incandescent areas were visible more than 2 km N of the original flow in addition to the hotspot at the active summit crater. On 14 May thermal imagery indicated a large anomaly and steam plume at the summit, a large anomaly on the W flank, and a lava flow trending N from the W flank. An anomaly also persisted over 2 km NW of the summit. By 16 June many anomalies were scattered over an area about 500 m wide and 2 km long on the W flank. More linear anomalies with scattered hotspots were present in 6 July and 22 August images on the W flank. Ash emissions were also visible in natural color images on 22 August (figure 14). Activity had declined by 21 October; although no hotspots were visible that day, clear skies showing the western edge of the flow field indicated the extent of new material when compared with an image from about one year earlier (figure 15). On 30 November and 20 December 2017, two hotspots were still visible at the summit.

Figure 14. Lava flows appeared on the NW flank of Langila and persisted for most of 2017. By 8 March large hot areas were visible more than 2 km N of the original flow in addition to the hotspot at the active summit crater. On 14 May thermal imagery indicated a large anomaly and steam plume at the summit, a large anomaly on the NW flank and a lava flow trending N from the NW flank. An anomaly also persisted more than 2 km NW of the summit. By 16 June many anomalies were scattered over an area about 500 m wide and 2 km long on the NW flank. More linear anomalies with scattered hotspots were present in 6 July and 22 August images on the NW flank. Ash emissions were also visible in natural color images on 22 August. Atmospheric penetration (bands 12, 11, 8a) and Natural color rendering (bands 4, 3, 2) courtesy of Sentinel Hub Playground.

Figure 15. A clear image of Langila on 21 October 2017 (right) shows the extent of new lava that emerged from the summit crater area during the year when compared with a similar image from 25 November 2016 (left). The image is about 7 km from top to bottom. Atmospheric penetration (bands 12, 11, 8a) courtesy of Sentinel Hub Playground.

Eruptive activity continued during 2018, but ash emissions were more frequent than during 2017 and fewer thermal anomalies were reported. The Darwin VAAC reported ash emissions in January, April-June, and September-December. A visitor to New Britain in late May 2018 captured images of ash plumes and experienced ashfall from a small boat offshore (figure 16). Satellite images showed ash plumes rising from the summit on 9 April, 9 May, 18 June, and 23 July (figure 17). Thermal anomalies at the summit could be seen during January, April-June, and August, along with a very weak one on 16 October 2018. Clear skies in November showed no thermal anomaly, but ash emissions were reported by the Darwin VAAC during both November and December. On 11 November a plume that rose to 3.1 km altitude drifted ESE and dissipated within a few hours. An ash plume on 20 December 2018 rose to 4.3 km altitude and drifted SSW for only about two hours before dissipating.

Figure 16. Ash plumes from Langila were witnessed by visitors offshore of New Britain in late May 2018. Left image was taken from the NW from a small boat. The right image was taken from Borgen Bay E of the volcano. Photographs courtesy of David Gorman, used with permission.

Figure 17. Sentinel-2 satellite imagery captured images of ash emissions each month during April-July 2018, including on 9 April (left) when the plume drifted SE and 23 July (right) when the plume drifted N. Natural color (bands 4, 3, 2) rendering courtesy of Sentinel Hub Playground.

Activity during 2019 and 2020. Although no VAAC notices were issued for Langila between December 2018 and August 2020, thermal anomalies in satellite images suggested possible continued activity during the period. Two hotspots were visible inside one of the summit craters on 10 March and 19 May 2019. Two MODVOLC thermal alerts appeared NE of the summit on 12 April. On 3 July, 29 September, and 31 October thermal anomalies were again present inside the summit crater. (figure 18).

Figure 18. Summit thermal anomalies appeared multiple times during 2019 at Langila in Sentinel-2 satellite imagery. Top left: Two hotspots were visible inside one of the summit craters and a gas plume drifted N on 10 March. Top right: Two MODVOLC thermal alerts were recorded close to the active crater on 12 April. Bottom: On 3 July and 31 October 2019 hotspots were visible at the crater. Atmospheric penetration rendering (bands 12, 11, 8A) courtesy of Sentinel Hub Playground and MODVOLC.

A small increase in thermal activity appeared in the MIROVA data during the second half of November 2019. On 30 November, in addition to an anomaly at the summit craters, an unusual thermal anomaly from an unknown source, possibly a fire, appeared about 1-2 km NE of the craters. It was elongate NE and about 200 m long. In the next image available on 5 December, a dark area appears immediately NE of where the anomaly had been (figure 19). By 25 December the freshly darkened area had faded to dark green.

Figure 19. A thermal anomaly and dark patch appeared on the NE flank of Langila in late November and early December 2019. The source is unknown, possibly from a fire. Top row: In addition to the thermal anomaly at the summit on 30 November 2019, an unusual thermal anomaly appeared about 1-2 km NE of the craters (white square). It was elongate NE and about 200 m long (left). It appears adjacent to an open area that is brighter green than the surrounding landscape in the Natural color image where a small dark spot at the site of the anomaly is visible (right). Bottom row: On 5 December 2019 the bright anomaly is gone, but a dark patch appears in both images where the bright green landscape was on 30 November. Natural color (bands 4, 3, 2) and Atmospheric penetration rendering (bands 12, 11, 8a) courtesy of Sentinel Hub Playground.

Either one or two thermal anomaly spots were present at the summit crater of Langila at least once each month during January-October 2020, and an ash plume drifted NNW from the summit on 20 July 2020 (figure 20). Beginning in late June, MIROVA recorded multiple low-level thermal anomalies which continued through October (figure 21). Four MODVOLC thermal alerts were issued on 2 August. That same day, the Darwin VAAC issued the first ash advisory of 2020 reporting an ash emission that rose to 2.4 km altitude and drifted NW. It was discernable in both the visible and RGB satellite imagery for about 12 hours before dissipating. An ash emission on 22 August rose to 1.8 km altitude and drifted NW. On 22 September, a plume rose to 2.7 km altitude and drifted NW. An ash plume on 5 October rose to 1.8 km altitude and drifted NW briefly before dissipating. Another plume the next day rose to 3.0 km altitude and drifted WSW for about four hours before disappearing from satellite imagery. On 22 October an ash plume was reported drifting S at 2.1 km altitude. It was only discernable in satellite imagery for about 30 minutes before dissipating. Two plumes were reported on 24 October that rose to 1.8-2.1 km altitude and briefly drifted N and NW.

Figure 20. Steam plumes and thermal anomalies were visible at the summit of Langila in satellite imagery at least once each month from January through October 2020, and ash emissions were seen in July. Top row: Single anomalies at the summit crater were recorded on 29 January, 18 May, and 22 June 2020. Bottom row: An ash plume was visible in Natural color imagery drifting NNW on 20 July, two anomalies at the summit crater were distinct on 21 August, and anomalies were visible through clouds and steam on 5 October 2020. Natural color (bands 4, 3, 2) and Atmospheric penetration rendering (bands 12, 11, 8a) courtesy of Sentinel Hub Playground.

Figure 21. A small increase in thermal activity at Langila was recorded by the MIROVA project during the second half of November 2019 at the same time that thermal anomalies were detected in Sentinel-2 satellite data. Multiple low to moderate power thermal anomalies were also recorded between June and November 2020. Graph shows Log Radiative Power from 18 September 2019 through October 2020. Courtesy of MIROVA.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Planet Labs, Inc. (URL: https://www.planet.com/); David Gorman, (URL: https://www.instagram.com/jimmyceb/, posted at https://twitter.com/SherineFrance/status/1002157440597741568).

May 2021 (BGVN 46:05) Cite this Report

Ash plumes, SO2 emissions, and thermal anomalies during November 2020-April 2021

Langila, located at the western tip of Papua New Guinea’s New Britain Island, consists of a group of four small overlapping cones. Frequent mild-to-moderate explosive eruptions with ash emissions have been recorded since the 19th century from three active summit craters. The current eruption period began in October 2015 and has recently been characterized by low-level thermal activity and ash plumes (BGVN 45:11). Similar activity continued during this reporting period of November 2020 through April 2021 using information primarily from the Darwin Volcanic Ash Advisory Center (VAAC) and satellite images.

The NASA Global Sulfur Dioxide page, using data from the TROPOMI instrument on the Sentinel-5P satellite, showed a few weak sulfur dioxide plumes during early December 2020 and late March 2021 that drifted in different directions (figure 22). The Darwin VAAC issued notices of ash plumes on 9 January 2021 to 4.9 km altitude that drifted W, on 13 January to 3 km that drifted WSW, and on 5 April to 1.5 km that drifted SW.

Figure 22. Small sulfur dioxide plumes were visible above Langila based on data from the TROPOMI instrument on the Sentinel-5P satellite. Faint plumes drifted W on 8 December (top left) 2020, N on 10 December (top right), SE on 18 March (bottom left) 2021, and NW on 20 March (bottom right). Small plumes were also present on most of those days originating from Manam (to the W) and Bagana (to the E) volcanoes. Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

MIROVA recorded a single low-power thermal anomaly was detected during early November, followed by four more during early December (figure 23). A low-power cluster of thermal anomalies resumed in mid-March that continued through the month. Three more anomalies were recorded in late April. The latter part of this thermal activity was also detected in Sentinel-2 infrared satellite imagery. A single thermal anomaly was visible at the summit crater beginning in February 2021, and in March a second thermal anomaly appeared that continued to be observed through April (figure 24).

Figure 23. Few low-power thermal anomalies at Langila were detected during early November (1) and early-to-mid-December (4) 2020 as recorded by the MIROVA graph (Log Radiative Power). A cluster of low-power thermal anomalies were detected in mid-March 2021 that continued through the month, followed by three anomalies in late April. Courtesy of MIROVA.

Figure 24. Weak thermal anomalies were visible at the summit of Langila in infrared satellite imagery during February through April 2021. Though clouds obscured most of the view on 12 February (top left), a single faint thermal anomaly was observed. On 9 March (top right) two thermal anomalies were observed at the summit, which were also visible on 6 (bottom left) and 18 (bottom right) April. On 18 April, the western thermal anomaly seemed to have decreased in strength slightly. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

February 2022 (BGVN 47:02) Cite this Report

Thermal anomalies, ash plumes, and sulfur dioxide plumes during May-December 2021

Langila consists of a group of four small overlapping cones and is located at the W tip of Papua New Guinea’s New Britain Island. Frequent mild-to-moderate explosive eruptions with ash emissions have been recorded since the 19th century from three active summit craters. The current eruption period began in October 2015 and has recently been characterized by intermittent low-level thermal activity, ash plumes, and sulfur dioxide plumes (BGVN 46:05). Similar activity continued during this reporting period of May through December 2021 using information primarily from the Darwin Volcanic Ash Advisory Center (VAAC) and satellite images.

Volcanism remained similar to recent activity. MIROVA recorded intermittent thermal activity at the summit during the reporting period, though between June and September the number and frequency of anomalies was low; during October through November, thermal activity increased (figure 25). According to the MODVOLC hotspot system, thermal anomalies were detected on 1, 15, and 20 October, 9 and 25 November, and 2 December. On clear weather days these small anomalies were visible in the summit crater in Sentinel-2 infrared satellite imagery, sometimes accompanied by gas-and-steam emissions (figure 26).

Figure 25. Intermittent thermal activity at Langila was shown in the MIROVA graph (Log Radiative Power) during May through December 2021. Activity was relatively low in both strength and frequency between June and September compared to October through December. Courtesy of MIROVA.

Figure 26. Sentinel-2 infrared satellite imagery showed a thermal anomaly at the summit of Langila on 3 May (top left), 22 June (top right), 12 July (bottom left), and 6 August (bottom right) 2021, sometimes accompanied by gas-and-steam emissions, as shown on 22 June and 12 July. On 6 August two thermal anomalies were observed at the summit. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

The NASA Global Sulfur Dioxide page, which shows data from the TROPOMI instrument on the Sentinel-5P satellite, showed intermittent weak sulfur dioxide plumes during July through December that drifted in different directions (figure 27). Occasional ash plumes were reported by the Darwin VAAC beginning on 3 May when an ash plume rose to 1.5 km altitude and drifted NE, based on HIMAWARI-8 satellite imagery, which was also accompanied by a thermal anomaly (figure 26). On 15 May an ash plume rose to 3 km altitude and drifted in two directions: S and NW. During 13-14 June ash plumes rose to 2.1-3 km altitude and drifted WNW and W, respectively. An ash plume that rose to 2.4 km altitude drifted WNW and W on 20 August and 11-12 September; a hotspot was also observed at the summit in satellite imagery during those days, according to the Darwin VAAC. A strong ash plume on 21 October rose to 4.6 km altitude and drifted NW.

Figure 27. Small sulfur dioxide plumes were visible above Langila based on data from the TROPOMI instrument on the Sentinel-5P satellite. Plumes drifted SW on 3 August (top left), NW on 5 August (top right), SW on 7 October (bottom left), and S on 23 November (bottom right) 2021. Plumes were also intermittently visible from Manam (to the W) and Bagana (to the E). Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

October 2022 (BGVN 47:10) Cite this Report

Weak thermal activity, occasional ash plumes, and sulfur dioxide plumes during January-September 2022

Langila is located at the W tip of Papua New Guinea’s New Britain Island and consists of a group of four small overlapping cones. Documented eruptions date back to the 19th century and were characterized by frequent mild-to-moderate explosive eruptions with ash emissions originating from three active summit craters. The current eruption period began in October 2015 and has recently consisted of intermittent, low-level thermal activity, ash plumes, and sulfur dioxide plumes (BGVN 47:02). Similar low activity continued during this report that covers January through September 2022 using information primarily from the Darwin Volcanic Ash Advisory Center (VAAC) and satellite images.

Activity was relatively low during the reporting interval, consisting primarily of intermittent thermal activity. The MIROVA (Middle InfraRed Observation of Volcanic Activity) graph showed low-power thermal anomalies mostly occurring from late April through September 2022 (figure 28). There were two anomalies detected during early-to-mid January and then a break in detected activity occurred during February through late April. Two small hotspots were detected during late April. There were five hotspots detected during May, four during June, eight during July, six during August, and eight during September. Some of this activity was also visible on clear weather days in Sentinel-2 infrared satellite imagery during April through September, sometimes accompanied by gas-and-steam emissions (figure 29).

Figure 28. Intermittent low-power thermal activity at Langila was shown in the MIROVA graph (Log Radiative Power) during January and late April through September 2022. There was a break in detected activity during mid-January through late April 2022. Courtesy of MIROVA.

Figure 29. Sentinel-2 infrared satellite imagery showed a single thermal anomaly at Langila on 18 May 2022 (top left), 7 June (top right), 22 July (bottom left), and 26 August (bottom right), sometimes accompanied by gas-and-steam emissions, as seen on 7 June and 22 July. Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

The NASA Global Sulfur Dioxide page, which shows data from the TROPOMI instrument on the Sentinel-5P satellite, showed occasional weak sulfur dioxide plumes during March through May 2022 that drifted in different directions (figure 30). Occasional ash plumes were reported by the Darwin VAAC beginning on 9 February when ash plumes were visible in HIMAWARI-8 satellite images and rose to 4.3 km altitude and drifted SW. On 6 March an ash plume rose to 3 km altitude and drifted SE; it dissipated within an hour. Another plume on 8 March rose to 3.7 km altitude and drifted NW; it dissipated within three hours. On 24 April an ash plume rose to 2.1 km altitude and drifted SW, before dissipating within 5.5 hours.

Figure 30. Small sulfur dioxide plumes were visible above Langila based on data from the TROPOMI instrument on the Sentinel-5P satellite. Plumes drifted NW on 16 March 2022 (top left), SW on 16 April (top right), 17 April (bottom left), and 18 May 2022 (bottom right). Plumes were also intermittently visible from Manam (to the W) and Bagana (to the E). Courtesy of the NASA Global Sulfur Dioxide Monitoring Page.

Information Contacts: Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground).

April 2023 (BGVN 48:04) Cite this Report

Thermal anomalies during clear weather through March 2023; ash plume on 20 October 2022

Frequent weak-to-moderate ash explosions and lava flows have been recorded since the 19th century from three active craters at the summit of Langila, located on Papua New Guinea’s New Britain Island. The current eruption period began in October 2015; recent activity has included low-level thermal activity, ash emissions, and SO₂ plumes (BGVN 47:10). Similar low-level activity continued during October 2022-March 2023 based on information from the Darwin Volcanic Ash Advisory Center (VAAC) and satellite images.

The only completely clear Sentinel-2 image during the reporting period showed a single bright hotspot at the SE crater on 20 October, and thermal anomalies were visible on 4 and 7 November in two craters (figure 31). Persistent clouds prevented observations until another anomaly in one crater was visible starting on 28 January and on other clear days through March 2023. Gas-and-steam emissions rising from the crater were also sometimes present. The MIROVA hotspot detection system also recorded only a few scattered thermal anomalies during October 2022-March 2023 (figure 32), which cloud cover was common. The MODIS-MODVOLC thermal detection system did not record any hotspots during this time.

Figure 31. Sentinel-2 infrared satellite images of Langila showed a persistent hotspot in the SE crater and occasional wispy gas-and-steam emissions during October 2022-March 2023. A thermal anomaly is seen here from one crater on 20 October (top) and two craters on 4 November 2022 (bottom). Sentinel-2 satellite images with “Atmospheric penetration” (bands 12, 11, 8A) rendering. Courtesy of Sentinel Hub Playground.

Figure 32. The MIROVA hotspot detection system (Middle InfraRed Observation of Volcanic Activity) graph showed intermittent low-power MODIS thermal anomalies at Langila into mid-November 2022, one in early January 2023, and then more frequent detections in the second half of March 2023. Courtesy of MIROVA.

A single strong SO₂ plume was observed by the TROPOMI instrument aboard the Sentinel-5P satellite during the reporting period, on 26 October 2022. According to the Darwin VAAC, an ash plume rose 2.7 km in altitude, or 1.4 km above the summit, on 20 October and drifted NW. The plume dissipated within five hours.

Information Contacts: Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Darwin Volcanic Ash Advisory Centre (VAAC), Bureau of Meteorology, Northern Territory Regional Office, PO Box 40050, Casuarina, NT 0811, Australia (URL: http://www.bom.gov.au/info/vaac/); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/).