Continued ash emissions during May-September 2009

During March-18 April 2009 (BGVN 34:03) seismicity and volcanism continued at Karymsky, and ash plumes were detected for hundreds of kilometers. This report discusses the interval May-October 2009, with some discussion of earlier seismicity. The key conclusion for this new interval is that seismicity has not stopped and occasional, though smaller ash plumes continued.

In the mid-May 2009 volcanic and seismic activity decreased considerably. The active fumarole on the NW slope produced gas-steam plumes, but no longer contained appreciable ash (figure 8).

Figure 8. Gas-steam emission seen on the NW side Koryaksky on 11 May 2009. The white snow on the volcano confirms the virtual absence of any ash in the plume. Photo by A. Socorenko.

On 2-3 June 2009, observers again saw small areas of snow that were dark gray, indicating some increased ash content. On 15-16 August 2009 instruments began to register a spasmodic volcanic tremor; seismicity increased, and on 17 August ash fell to the SW, forming a deposit 1 mm thick (figure 9).

Figure 9. Ash plume from a vent on NW slope of Koryaksky. Snow on the slope covered fresh ashfall. Dark area around vent is due to local heating and melting of snow cover. Photo taken on 18 August 2009 by S. Chirkov.

Seismic analysis. Seliverstov (2009) analyzed seismicity for May 2008 to 10 June 2009, looking at events larger than Ks 4 (Class 4 earthquakes, roughly those larger than M ~ 1.2) and found a spatial and temporal pattern to this stronger seismicity. During March 2008 a prominent swarm of earthquakes was often centered at about 5-10 km depth. Smaller earthquakes were also seen around that time, several at ~ 12 km depth, and some at 15 km depth. This stronger seismicity then waned for several months until late June. During August 2008 to 10 June 2009, earthquakes were numerous, often centered near 5 km depth.

Figure 10 shows a representative set of hypocenters during 3 January 2009-6 November 2009. The pattern shown was similar to that seen during various months during 2008 through mid-2009. Other patterns during 2008 to mid-2009 included intervals where epicenters dipped, as noted in the analysis presented by Seliverstov (2009). Despite decreased volcanic activity, the elevated seismicity remained until at least 10 June 2009.

Figure 10. Seismicity of Koryaksky (and Avachinsky, to the SE) recorded during May-October 2009. Map shows location and depths of earthquakes (white line is cross-section AB. Cross-section shows hypocenters within 20 km depth. Courtesy of the Kamchatka Branch of the Geophysical Service, Russian Academy of Sciences (KB GS RAS).

The number of earthquakes recorded within 10-15 km of the summit during January through October 2009 by the KB GS RAS peaked in April with 422 events, and again in August with 245 events. Otherwise, the interval commonly had monthly totals of 100-200 with the lowest during January (59 events) and October (37 events).

References. Seliverstov, N., 2009, The activity Koryaksky volcano, Kamchatka, Vestnik KRAUNC, Earth Science Series; Petropavlovsk-Kamchatsky, 2009, v. 13, p.7-9 [ISSN 1816-5524]. In Russian.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS), Sergey Senukov, Russia (URL: http://www.emsd.ru/); Alexander Socorenko and Sergei Chirkov, IV&S FED RAS; Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

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

March 1994 (BGVN 19:03) Cite this Report

Significant increase in seismic activity centered at 5 km depth

During 6 March-8 April there was a significant increase in seismic activity. Most of the 43 seismic events recorded took place at a depth of 5 km beneath the volcano. The three strongest earthquakes occurred on 4 April. The level of seismic activity beneath the volcano decreased during the second week of April; only a few weak earthquakes were registered at depths of 5-10 km. On 8 April the Level of Concern Color Code was upgraded to Yellow from Green, indicating that an eruption is possible with little or no additional warning.

Information Contacts: V. Kirianov, IVGG.

April 1994 (BGVN 19:04) Cite this Report

Seismicity returns to background levels; alert status lowered

The increased level of seismicity . . . continued to be recorded beneath the volcano (1-2 earthquakes/day) through the end of April. These high-frequency tectonic events (with some unusual characteristics) occurred at 2-12 km depth with a maximum magnitude of 2. This type of event at this depth range has not been identified since the present seismic net on the volcano was installed in 1982. Although the seismic activity continued into early May at a rate of 1-2 earthquakes/day, the lack of additional increase led to the downgrading of the Level of Concern Color Code back to Green.

Seismicity beneath the Koryaksky-Avachinsky area increased above background levels in mid-May to a rate of 6-9 earthquakes/day. During a 2-day period, 18 earthquakes were detected at ~12 km (11 May) and 0-9 km depth (12 May). Seismicity had returned to background levels by 26 May.

Information Contacts: V. Kirianov, IVGG.

September 1996 (BGVN 21:09) Cite this Report

Background seismicity in late July and August

Seismicity was at or a little above normal background levels in late July and August. Historical activity at Koryaksky has been largely fumarolic, although a weak explosive eruption took place in 1956-57 from the summit crater and a radial fissure on the upper NW flank.

Information Contacts: Tom Miller, Alaska Volcano Observatory (AVO), 4200 University Drive, Anchorage, AK 99508-4667, USA; Vladimir Kirianov, Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanic Geology and Geochemistry, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia.

November 1997 (BGVN 22:11) Cite this Report

Above-background seismicity in late December

Seismicity was at normal background levels from September 1996 through mid-December 1997; the period of normal activity began in July 1996 (BGVN 21:09). However, during 22-29 December, seismicity was reported above background level.

Information Contacts: Vladimir Kirianov, Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanic Geology and Geochemistry, Piip Ave. 9, Petropavlovsk- Kamchatskiy 683006, Russia; Tom Miller, Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.

December 2003 (BGVN 28:12) Cite this Report

News report of a 12 December, M 3.6 earthquake at 6 km depth

Our last report for Koryaksky was BGVN 22:11, discussing seismicity in 1997. According to a Russian Information Agency Novosti press report, on 12 December 2003 instruments detected an M 3.6 earthquake followed by ~ 2 hours of seismicity at ~ 6 km depth beneath Koryaksky. A cyclonic weather system over the peninsula obstructed visual observations.

Information Contacts: Russian Information Agency Novosti (URL: http://russia-insider.com/).

January 2009 (BGVN 34:01) Cite this Report

Seismicity, then ash eruptions, after ~ 51-year repose

Koryaksky, which had lacked fumarolic activity during the last ~ 51 years, began steaming after seven months of local seismicity. The increased seismicity became prominent in March 2008 (figure 1) and the first steaming was recorded on 6 October 2008. The first fumarole vent to appear was located at ~ 3 km elevation on the upper NW slope. Koryaksky, a large snow-laden stratovolcano, forms the most prominent feature of the Avachinskaya volcano group. Episodes of elevated seismicity have previously occurred, as reported in December 2003 (BGVN 28:12).

Figure 1. Seismicity of Koryaksky (and Avachinsky, to the SE) recorded during February 2008-February 2009. a) A map of the region showing location and depths of earthquakes. The white line is trace of cross section AB; a 35-km-diameter circle encloses epicenters of earthquakes plotted in c). b) Histogram showing daily earthquakes with respect to time; ascending curve is the cumulative number of earthquakes (reaching a total of 970 for the interval). c) Hypocenters projected onto the vertical plane of cross section AB. Courtesy of KB GS RAS.

Only two earthquakes struck on 23 December 2008, both at ~ 5 km depth. Observers also heard a booming sound from the volcano at night. NOAA 17 satellite data collected at 2357 UTC on 23 December revealed that a dense ash plume extended over 60 km laterally, and an ash-poor ash plume continued beyond that for another 140 km NE. During 24-25 December observers in the Nalychevo valley saw a dark ash column rise about 200-300 m from the upper NW-flank vent.

On 28 December 2008 moderately explosive vulcanian-type eruptions occurred. Ash plumes rose to ~ 4 km altitude and extend NW. Observers also saw significant fumarolic activity at two vents. During a break in cloud cover on 30-31 December observers saw gas-and-steam plumes, which were thought to contain small amounts of ash. They drifted along the surface of the NW flank, some reaching ~ 4 km altitude. A 2 January KVERT report noted background seismicity during 31 December-6 January, with 1-7 volcanic earthquakes per day and possible episodes of tremor during 30 December to 1 January.

During 6-8 January 2009 strong fumarolic activity continued. According to visual data, gas-steam plumes extended SW from three vents. Gray deposits were visible at the area near the summit. Figures 2 and 3 illustrate the scene on 8 and 10 January 2009. Strong fumarolic activity also prevailed on 14 and 18-19 February 2009.

Figure 2. Gas and steam escaping from Koryaksky on 8 January 2009. Three vents on the NW slope trace an older fissure. Photo by Alexandr Socorenko.

Figure 3. View of Koryaksky looking W from Petropavlovsk on 10 January 2009. The photo was taken from the roof of Institute of Volcanology and Seismology. Photo by Alexandr Socorenko.

KVERT issued reports on 4 March 2009 noting increased activity, with some ash-bearing plumes extending over 200 km to the NE-ENE on 3-4 March. For the previous week, seismicity was again at background. Ash deposits were identified both on the summit and in the saddle to Avachinsky. At the latter area on 4 March, the deposits reached 1-2 mm thickness.

In a 5 March report, KVERT noted plumes containing small amounts of ash rising to 3.7 km and extending over 220 km. They blew to the ENE, E, and SE on 3-5 March. Koryaksy's N flank contained fresh ash deposits ~ 4.0 cm thick. The crater contained a weak, new fumarole.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanology and Seismology (IV&S) Far East Division, Russian Academy of Sciences (FED RAS); Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs, http://www.emsd.ru/~ssl/monitoring/main.htm); Alexander Sokorenko, IV&S; Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

March 2009 (BGVN 34:03) Cite this Report

Increased ash emissions during March and April 2009

Koryaksky ended ~ 51 years without fumarolic activity with an eruption late in 2008. Activity that began on about 24 December 2008 continued through 5 March 2009 (BGVN 34:01). Fresh ash deposits in early March could be seen on both the summit, E, and SSW slopes of Koryaksky, and on the NNW slope of Avachinsky (figure 4). Between the two volcanoes, the early March ash deposits reached 1-2 mm thick.

Figure 4. (top) Ash plume from Koryaksky (peak at left) extending to the ESE in an eruption that left deposits of ash on Koryaksky and Avachinsky (peak at right). (bottom) Ash deposits on Koryaksky on the same date. Both photos from the town of Petropavlovsk-Kamchatsky on 7 March 2009 by A. Sokorenko.

Numerous plumes were observed during this reporting interval, 6 March to mid-April 2009 (table 1). A report from 8-14 April noted the presence of two vents on the NW flank. A small SO₂ plume was noted on 20 April. Seismicity often fluctuated, with considerable intervals at background level punctuated by intervals where it was elevated. Occasional tremor was recorded, but it was often weak (low amplitude).

Table 1. A compilation of eruptive plume behavior from Koryaksky based on information from the Yelizovo Airport, KVERT, and KEMSD (the Kamchatkan Experimental and Methodical Seismological Department). The data were initially compiled by the Tokyo VAAC in reports for aviators in an effort to avoid aircraft encounters with volcanic ash. Few of the plumes were considered ash rich, most were considered as gas plumes containing small amounts of ash. Courtesy of the Tokyo VAAC.

KVERT reported that seismic activity at Koryaksky was elevated on 6 and 8 March and at background levels during 7 and 9-13 March. Observers reported that gas plumes containing a small amount of ash rose to an altitude of 4 km and drifted in multiple directions during the week of 11-17 March. The plumes were also seen on satellite imagery.

An eruption on 9 April 2009 followed an increase in the number of local earthquakes and tremor during the previous month (figure 5). The total number of earthquakes during February 2008-December 2008 was 717. That was less than the total of 766 for the first four months in 2009, which were as follows: January, 58; February, 195; March, 239; and April, 274. High level gas-steam and ash emissions occurred during March-April. Some plumes extended more than 200 km (table 1).

Figure 5. Seismicity of Koryaksky (and Avachinsky, to the SE) recorded during January-April 2009. Map (left) shows location and depths of earthquakes (white line is cross-section AB; 20-km-diameter circle encloses epicenters of earthquakes plotted on histogram. Cross-section shows hypocenters projected onto the vertical plane along AB. Histogram shows daily Koryaksky earthquakes with respect to time; ascending curve is the cumulative number of earthquakes (reaching a total of 652 for the interval). Courtesy of the Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS).

On 9 April a photo was taken showing a strong ash plume emerging from fissures in the glacier on Koryaksky's NW flank. On 13 April a flight over the area enabled scientists to measure temperature around two vents (figures 6 and 7). Temperatures of the vent areas reached 400°C. This situation was attributed to glacial instability owing to melting parts of the glacier near the vents.

Figure 6. A photo taken from Petropavlovsk-Kamchatsky (~35 km N of the volcano) illustrating powerful ash-bearing emissions from the NW flank of Koryaksky. Photo taken by Sergei Ushakov 9 April 2009.

Figure 7. A photo showing two vents on the NW flank of Koryaksky. The upper plume is ash rich, the other contains only gas and steam. Photo taken by Alexander Sokorenko on 18 April 2009.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanology and Seismology (IV&S), Far East Division, Russian Academy of Sciences (FED RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); Kamchatka Branch of the Geophysical Service, Russian Academy of Sciences (KB GS RAS), Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.emsd.ru/~ssl/monitoring/main.htm); Alexander Sokorenko and Sergey Ushakov, IV&S; Kamchatkan Experimental and Methodical Seismological Department (KEMSD), GS RAS, Russia; Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).

September 2009 (BGVN 34:09) Cite this Report

Continued ash emissions during May-September 2009

During March-18 April 2009 (BGVN 34:03) seismicity and volcanism continued at Karymsky, and ash plumes were detected for hundreds of kilometers. This report discusses the interval May-October 2009, with some discussion of earlier seismicity. The key conclusion for this new interval is that seismicity has not stopped and occasional, though smaller ash plumes continued.

In the mid-May 2009 volcanic and seismic activity decreased considerably. The active fumarole on the NW slope produced gas-steam plumes, but no longer contained appreciable ash (figure 8).

Figure 8. Gas-steam emission seen on the NW side Koryaksky on 11 May 2009. The white snow on the volcano confirms the virtual absence of any ash in the plume. Photo by A. Socorenko.

On 2-3 June 2009, observers again saw small areas of snow that were dark gray, indicating some increased ash content. On 15-16 August 2009 instruments began to register a spasmodic volcanic tremor; seismicity increased, and on 17 August ash fell to the SW, forming a deposit 1 mm thick (figure 9).

Figure 9. Ash plume from a vent on NW slope of Koryaksky. Snow on the slope covered fresh ashfall. Dark area around vent is due to local heating and melting of snow cover. Photo taken on 18 August 2009 by S. Chirkov.

Seismic analysis. Seliverstov (2009) analyzed seismicity for May 2008 to 10 June 2009, looking at events larger than Ks 4 (Class 4 earthquakes, roughly those larger than M ~ 1.2) and found a spatial and temporal pattern to this stronger seismicity. During March 2008 a prominent swarm of earthquakes was often centered at about 5-10 km depth. Smaller earthquakes were also seen around that time, several at ~ 12 km depth, and some at 15 km depth. This stronger seismicity then waned for several months until late June. During August 2008 to 10 June 2009, earthquakes were numerous, often centered near 5 km depth.

Figure 10 shows a representative set of hypocenters during 3 January 2009-6 November 2009. The pattern shown was similar to that seen during various months during 2008 through mid-2009. Other patterns during 2008 to mid-2009 included intervals where epicenters dipped, as noted in the analysis presented by Seliverstov (2009). Despite decreased volcanic activity, the elevated seismicity remained until at least 10 June 2009.

Figure 10. Seismicity of Koryaksky (and Avachinsky, to the SE) recorded during May-October 2009. Map shows location and depths of earthquakes (white line is cross-section AB. Cross-section shows hypocenters within 20 km depth. Courtesy of the Kamchatka Branch of the Geophysical Service, Russian Academy of Sciences (KB GS RAS).

The number of earthquakes recorded within 10-15 km of the summit during January through October 2009 by the KB GS RAS peaked in April with 422 events, and again in August with 245 events. Otherwise, the interval commonly had monthly totals of 100-200 with the lowest during January (59 events) and October (37 events).

References. Seliverstov, N., 2009, The activity Koryaksky volcano, Kamchatka, Vestnik KRAUNC, Earth Science Series; Petropavlovsk-Kamchatsky, 2009, v. 13, p.7-9 [ISSN 1816-5524]. In Russian.

Information Contacts: Kamchatka Volcanic Eruptions Response Team (KVERT), Far East Division, Russian Academy of Sciences, 9 Piip Blvd., Petropavlovsk-Kamchatsky, 683006, Russia (URL: http://www.kscnet.ru/ivs/); Kamchatka Branch of the Geophysical Service of the Russian Academy of Sciences (KB GS RAS), Sergey Senukov, Russia (URL: http://www.emsd.ru/); Alexander Socorenko and Sergei Chirkov, IV&S FED RAS; Tokyo Volcanic Ash Advisory Center (VAAC), Tokyo, Japan (URL: http://ds.data.jma.go.jp/svd/vaac/data/).