Smithsonian / USGS Weekly Volcanic Activity Report

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday and averaging 16 reported volcanoes, this is not a comprehensive list of all eruptions this week, but rather a summary of activity that meet criteria discussed in the "Criteria and Disclaimers" section below.

Volcanic activity reported here is preliminary and subject to change. Carefully reviewed, detailed narratives over longer time periods are published as reports of the Bulletin of the Global Volcanism Network available through volcano profile pages.

Smithsonian / USGS Weekly Volcanic Activity Report for the week of 19 July-25 July 2023
Name	Country	Volcanic Province	Eruption Start Date	Report Status
Bagana	Papua New Guinea	Solomon Volcanic Arc	2000 Feb 28 (in or before)	New
Dempo	Indonesia	Sunda Volcanic Arc	—	New
Fagradalsfjall	Iceland	Iceland Neovolcanic Rift Volcanic Province	—	New
Langila	Papua New Guinea	Bismarck Volcanic Arc	2015 Oct 22 (?)	New
Lokon-Empung	Indonesia	Sangihe Volcanic Arc	—	New
Mayon	Philippines	Eastern Philippine Volcanic Arc	—	New
Nishinoshima	Japan	Ogasawara Volcanic Arc	—	New
Piton de la Fournaise	France	Reunion Hotspot Volcano Group	—	New
Shishaldin	United States	Aleutian Ridge Volcanic Arc	—	New
Ubinas	Peru	Central Andean Volcanic Arc	—	New
Ulawun	Papua New Guinea	Bismarck Volcanic Arc	—	New
Aira	Japan	Ryukyu Volcanic Arc	2017 Mar 25	Continuing
Cleveland	United States	Aleutian Ridge Volcanic Arc	—	Continuing
Ebeko	Russia	Kuril Volcanic Arc	2022 Jun 11	Continuing
Great Sitkin	United States	Aleutian Ridge Volcanic Arc	2021 May 25	Continuing
Kanlaon	Philippines	Negros-Sulu Volcanic Arc	—	Continuing
Karangetang	Indonesia	Sangihe Volcanic Arc	—	Continuing
Klyuchevskoy	Russia	Eastern Kamchatka Volcanic Arc	—	Continuing
Krakatau	Indonesia	Sunda Volcanic Arc	—	Continuing
Lewotolok	Indonesia	Sunda Volcanic Arc	—	Continuing
Merapi	Indonesia	Sunda Volcanic Arc	2020 Dec 31	Continuing
Reventador	Ecuador	Northern Andean Volcanic Arc	2008 Jul 27	Continuing
Semeru	Indonesia	Sunda Volcanic Arc	2017 Jun 6	Continuing
Sheveluch	Russia	Eastern Kamchatka Volcanic Arc	1999 Aug 15	Continuing
Suwanosejima	Japan	Ryukyu Volcanic Arc	2004 Oct 23	Continuing
Whakaari/White Island	New Zealand	Taupo Volcanic Zone	2024 May 24	Continuing

All times are local unless otherwise stated.

Bagana (Papua New Guinea) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Bagana
Solomon Volcanic Arc

According to new articles, more than 7,000 people needed temporary accommodations due to the eruption at Bagana, with about 1,000 of those in evacuation shelters. Ashfall was deposited over a broad area, contaminating water supplies, affecting crops, and collapsing some roofs and houses in rural areas. Schools were temporarily shut down. The Alert Level was lowered to Stage 2 (on a four-level scale).

Sources: Radio New Zealand, The National

Dempo (Indonesia) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Dempo
Sunda Volcanic Arc

PVMBG reported that at 2115 on 25 July an eruption at Dempo produced a white-and-gray ash plume that rose at least 2 km above the summit and drifted S and SW. An eruptive event was recorded at 1547 on 26 July but weather conditions prevented views of the volcano. At 2115 PVMBG issued a Volcano Observatory Notice for Aviation (VONA) stating that activity was increasing. The Alert Level remained at 2 (on a scale of 1-4), and the public were reminded to stay 1 km away from the crater and as far as 2 km on the N flank.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Fagradalsfjall (Iceland) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Fagradalsfjall
Iceland Neovolcanic Rift Volcanic Province

IMO reported that lava continued to erupt from main vent at Fagradalsfjall during 19-26 July with no significant changes. Lava from the main vent, which was about 90 x 40 m, continued to advance SSW and sulfur dioxide plumes rose 1-2 km above the crater rim. Seismicity had decreased since the onset of the eruption and was concentrated at the N end of the dike and to the E of Keilir. The lava effusion rate averaged 8 cubic meters per second during 18-23 July based on calculations from the University of Iceland, the Icelandic Institute of Natural History, and the National Land Survey of Iceland. They also estimated that the total erupted volume was about 12.4 million cubic meters, and the flow field covered an area of about 1.2 square kilometers. According to a news article part of the N crater rim collapsed just before noon on 24 July, sending lava flows along a new channel, still mainly to the S but spreading more E. The hiking trails were no longer accessible 24 hours a day and were going to be closed at 1800 each day. Firefighters continued to control the burning vegetation set on fire by the lava. The Aviation Color Code remained at Orange (the third level on a four-color scale).

Sources: Icelandic Meteorological Office (IMO), Icelandic National Broadcasting Service (RUV)

Langila (Papua New Guinea) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Langila
Bismarck Volcanic Arc

The Darwin VAAC reported that ash plumes at Langila were visible in satellite images on 19 July rising 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifting SE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Lokon-Empung (Indonesia) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Lokon-Empung
Sangihe Volcanic Arc

PVMBG reported continuing daily steam-and-gas emissions at Lokon-Empung during 19-25 July. White plumes with variable densities rose as high as 250 m above the crater rim and drifted W and N. The Alert Level remained at 3 (on a scale of 1-4) and the public was reminded not to approach Tompaluan Crater within a radius of 2.5 km.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Mayon (Philippines) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Mayon
Eastern Philippine Volcanic Arc

PHIVOLCS reported that the eruption at Mayon continued during 19-25 July, with slow lava effusion from the summit crater feeding lava flows on the S, SE, and E flanks. The length of the lava flow in the Mi-Isi (S) drainage remained at 2.8 km and the flow in the Bonga (SE) drainage advanced to 2.8 km by 23 July. The lava flow in the Basud drainage on the E flank did not advance, remaining 600 m long. Collapses at the lava dome and from the lava flows produced incandescent rockfalls and pyroclastic density currents (PDCs, or pyroclastic flows) that descended the Mi-Isi, Bonga, and Basud drainages as far as 4 km. Seismicity was dominated by weak low-frequency volcanic earthquakes (LFVQs) originating from a shallow source and were associated with a rapid release of volcanic gases from the summit crater. Some of the events produced audible thunder-like sounds and short dark ash plumes that drifted SW. Between 1733 on 18 July and 0434 on 19 July there were 30 of these events (called “ashing” by PHIVOLCS) recorded by seismic, infrasound, and visual and thermal monitors; each lasted 20-40 seconds long and generated ash plumes that rose 150-300 m above the summit. Sulfur dioxide emissions were reported on most days; variable amounts averaged between 1,581 and 3,135 tonnes per day, with the highest value recorded on 24 July. Each day seismic stations recorded 137-175 rockfall events, 3-4 PDC events, and 5-304 LFVQs. During 19-20 the network recorded three ashing events. At 1956 on 21 July a short-lived (28 seconds) ejection of lava was accompanied by seismic and infrasound signals. The Disaster Response Operations Monitoring and Information Center (DROMIC) reported that as of 1800 on 24 July there were 5,372 families, or 18,782 individuals, that were either in evacuation shelters or staying in other types of alternative housing. The Alert Level remained at 3 (on a 0-5 scale) and residents were reminded to stay away from the 6-km-radius Permanent Danger Zone (PDZ). PHIVOLCS recommended that civil aviation authorities advise pilots to avoid flying close to the summit.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Disaster Response Operations Monitoring and Information Center (DROMIC)

Nishinoshima (Japan) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Nishinoshima
Ogasawara Volcanic Arc

The Tokyo VAAC reported that an ash plume from Nishinoshima was seen by a pilot and identified in a satellite image at 0630 on 21 July drifting S at an altitude of 3 km (10,000 ft) a.s.l.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)

Piton de la Fournaise (France) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Piton de la Fournaise
Reunion Hotspot Volcano Group

OVPF reported that the eruption that began on 2 July at Piton de la Fournaise was ongoing during 19-25 July, though weather conditions often obscured views. The active cone was about 30 m tall and located on the upper part of Grandes Pentes, SE of Enclos Fouqué, at approximately 1,720 m a.s.l. Volcano-tectonic earthquake events fluctuated throughout the week but remained low relative to the onset of the eruption. The lava lake in the cone was low and lava was occasionally ejected above the rim. Lava was mainly transported through lava tubes and was not visible immediately near the cone. The longest part of the flow did not advance and remained stalled 1.8 km from the road, but the flow field continued to widen and thicken. Breakouts were visible in areas between 1,300 m and 1,500 m elevation. The total volume of lava effused since the beginning of the eruption was an estimated 8.5 +/- 3 million cubic meters by 22 July.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)

Shishaldin (United States) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Shishaldin
Aleutian Ridge Volcanic Arc

AVO reported that the effusive and explosive eruption at Shishaldin was continuing during 18-25 July. Satellite images acquired on 18 July, after a period of activity where ash plumes rose to 9.1 km (30,000 ft) a.s.l., showed ash deposits extending to the SW as well as to the SSE where they reached the shore of Unimak Island. Pyroclastic flow deposits up to 3 km long were visible on the N, E, and S flanks, and deposits from lahars triggered by those events extended farther down the flanks. Weather clouds often obscured webcam and satellite views of the summit during 19-21 July, though elevated surface temperatures consistent with low-level eruptive activity in the summit crater were visible in some clear images. Seismicity was low and no infrasound signals indicating explosive activity were detected.

Elevated surface temperatures detected in satellite images overnight during 21-22 July, despite weather cloud cover, were consistent with increased lava effusion. Sulfur dioxide emissions were detected in satellite data midday on 22 July. In a special notice issued at 1653 on 22 July AVO noted that eruptive activity had intensified over the previous six hours, characterized by a steady increase in seismic tremor and intermittent infrasound signals consistent with small explosions. Pilots first reported low-level ash plumes at around 1900. By 2330 the ash plume had risen to 9 km (30,000 ft) a.s.l. based on additional pilot reports and satellite images. The Aviation Color Code was raised to Red (the highest color on a four-color scale) and the Volcano Alert Level was raised to Warning (the highest level on a four-level scale) at 2343. Ash emissions were sustained for just over an hour (from 2320 on 22 July to 0030 on 23 July) and rose as high as 11 km (36,100 ft) a.s.l.; by the end of the period ash plume altitudes had declined to 4.6 km (15,000 ft) a.s.l. Seismic tremor peaked at 0030 on 23 July and then began to rapidly decline at 0109. Activity had significantly declined, and tremor levels were low, by 0418; AVO lowered the Volcano Alert Level to Watch and the Aviation Color Code to Orange. The ash plume had detached and was drifting NE along the Alaska Peninsula. Bursts of increased seismicity were detected by the seismic network throughout the morning but overall remained at low levels. Elevated surface temperatures were identified in satellite images until about 0600. During 23-24 July pilots reported seeing vigorous steam-and-gas plumes rising to about 3 km (10,000 ft) a.s.l.; the plumes may have contained minor amounts of ash. Seismicity was low.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Ubinas (Peru) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Ubinas
Central Andean Volcanic Arc

Instituto Geofísico del Perú (IGP) and Instituto Geológico Minero y Metalúrgico (INGEMMET) reported that the eruption at Ubinas continued during 19-25 July. According to IGP there were 46 volcano-tectonic earthquakes indicating rock fracturing and 122 long-period earthquakes signifying the movement of gas and magma recorded by the seismic network during 17-23 July. In addition, there were seven seismic signals associated with major explosive events, and 9-14 hours of seismic signals related to ash emissions.

Both IGP and INGEMMET reported a few notable explosions and ash plumes during the week. At 0530 on 20 July an explosion produced an ash plume that rose 3-4.5 km above the crater rim and drifted W and SW. Another explosion the next day, at 0922 on 21 July, produced an ash-and-gas plume that rose 5 km above the crater rim. Ashfall was reported in Querapi (4.5 km SE), Ubinas (6.5 km SSE), Tonohaya (7 km SSE), Anascapa (11 km SE), Sacohaya, San Miguel (10 km SE), Escacha, Huatagua (14 km SE), Huarina, Escacha (9 km SE), Matalaque (17 km SSE), Logén, Santa Lucía de Salinas, and Salinas de Moche. An explosion at 1323 on 22 July generated an ash plume that rose 5.5 km and drifted NE, E, and SE. The Alert Level remained at Orange (the third level on a four-color scale) and the public was warned to stay 4 km away from the crater.

Sources: Instituto Geofísico del Perú (IGP), Instituto Geológico Minero y Metalúrgico (INGEMMET)

Ulawun (Papua New Guinea) | 19 July-25 July 2023 | New Activity / Unrest Cite this Report

Ulawun
Bismarck Volcanic Arc

RVO reported that minor ash emissions at Ulawun began on 18 July, and during the morning of 19 July brown-to-gray emissions with low ash content were rising a few hundred meters above the crater rim and drifting SE. During 20-25 July steam-and-gas plumes with minor-to-moderate amounts of ash rose from the summit crater and rapidly dispersed. The emissions drifted in various directions, but mainly NW; minor ashfall was reported in areas downwind. Sulfur dioxide emissions were detected in satellite images on 21 and 24 July. Seismicity had begun increasing on 16 July, with RSAM values climbing at a slow but erratic rate, and peaking on 18 July. Afterwards RSAM values decreased and remained at low levels (150-200); seismicity was dominated by continuous volcanic tremors. RSAM values steadily increased to 550 during 0400-1400 on 22 July and fluctuated at moderate levels of 300-350 through 23 July. Values were variable on 24 July between values of 400 to 700. The Alert Level remained at Stage 1 (the lowest level on a four-level scale).

Source: Rabaul Volcano Observatory (RVO)

Aira (Japan) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Aira
Ryukyu Volcanic Arc

JMA reported ongoing activity at both Minamidake Crater and Showa Crater (Aira Caldera’s Sakurajima volcano) during 16-24 July. Very small eruptive events occasionally occurred at Minamidake and incandescence was observed at night. An eruptive event at Showa on 16 July produced an ash plume that rose 1.2 km above the crater rim and drifted N. An explosion at the same crater at 2314 produced an ash plume that rose 1.8 km above the crater rim and drifted N, and also ejected blocks 300-500 m from the vent. Explosions at 1224 and 1232 on 17 July generated ash plumes that rose 2-2.5 km and drifted N, with blocks ejected 500-800 m from the vent. At 2044 on 17 July an ash plume from an explosion rose 1.2 km and drifted N. Sulfur dioxide emissions were very high, averaging 3,200 tons per day on 20 July. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 km away from both craters.

Source: Japan Meteorological Agency (JMA)

Cleveland (United States) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Cleveland
Aleutian Ridge Volcanic Arc

AVO reported that numerous earthquakes at Cleveland have been detected by the local seismic network during the previous week and 37 of the events were large enough to be located. Earthquake hypocenters shallowed from depths of less than 18 km during the beginning to depths less than 6 km by the end of the week. The earthquakes were small, at magnitudes less than 2, but the rate of events was unusual for Cleveland. The seismicity along with elevated surface temperatures at the summit crater frequently identified in satellite images and continued gas-and-steam emissions suggested an increased likelihood of a future eruption. The Volcano Alert Level for Cleveland to Advisory (the second level on a four-level scale) and the Aviation Color Code to Yellow (the second color on a four-color scale) at 1218 on 19 July. Earthquakes continued to be detected (but were too small to be located) during 21-23 July. Weather clouds mostly obscured views of the volcano in satellite and web camera images, though minor steaming from the summit occurred during 23-24 July.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Ebeko (Russia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Ebeko
Kuril Volcanic Arc

KVERT reported that moderate explosive activity at Ebeko was ongoing during 13-20 July. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 17-19 July generated ash plumes that rose as high as 4.5 km (14,800 ft) a.s.l and drifted to the NW and SE. Thermal anomalies were identified in satellite images on 17 and 19 July; weather clouds obscured views on other days. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Great Sitkin (United States) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Great Sitkin
Aleutian Ridge Volcanic Arc

AVO reported that slow lava effusion continued at Great Sitkin during 19-25 July, producing a thick lava flow in the summit crater. About 10-20 daily local earthquakes were recorded by the seismic network during 19-23 July, and about 20 low-frequency seismic events were detected during 21-22 July. Weather clouds often obscured satellite and webcam views, though a clear image from 19 July showed minor steaming from the lava surface and minimal change to the overall lava flow extent. Minor steaming was again visible in satellite images during 22-24 July. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Kanlaon (Philippines) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Kanlaon
Negros-Sulu Volcanic Arc

PHIVOLCS issued a special notice for Kanlaon at 1000 on 21 July, noting increased seismicity. The seismic network detected 35 volcano-tectonic earthquakes between 2200 on 20 July and 0906 on 21 July at depths of 12-15 km beneath the summit crater. The earthquakes had local magnitudes of 0.9-2.3. Ground deformation data from continuous GPS and electronic tilt data had been recording inflation at the mid-flanks of the volcano since March. Sulfur dioxide emissions at the summit crater averaged 786 tonnes per day (t/d) on 18 July and 230 t/d on 21 July, slightly higher than the average of 566 t/d measured in March. The number of volcano-tectonic earthquakes decreased during the rest of the week; there were 16 recorded during 21-22 July and 1-2 daily earthquakes during 23-25 July. The Alert Level remained at 1 (on a scale of 0-5) and PHIVOLCS reminded the public to remain outside of the 4-km-radius Permanent Danger Zone.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Karangetang (Indonesia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Karangetang
Sangihe Volcanic Arc

PVMBG reported that dense white gas-and-steam plumes from Karangetang were visible rising as high as 100 m and drifting E, NE, NW, and W on most days during 19-25 July. The Darwin VAAC noted that ash plumes rose as high as 2.4 km (8,000 ft) a.s.l. at 1710 on 21 July, at 1530 on 22 July, and at 0850 on 23 July, that drifted NE and E. According to a news source, lava avalanches traveled more than 1.7 km down the Kahetang drainage, 1 km down the Batuawang and Batang drainages, 800 m down the Timbelang drainage, and about 1.5 km down the West Beha drainage during 21-22 July. Dense gray-to-white plumes sometimes accompanied the lava avalanches. The Alert Level remained at 3 (on a scale of 1-4) and the public were advised to stay 2.5 km away from Main Crater with an extension to 3.5 km on the S and SE flanks.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC), Antara News, Antara News

Klyuchevskoy (Russia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Klyuchevskoy
Eastern Kamchatka Volcanic Arc

KVERT reported that the minor Strombolian eruption at Klyuchevskoy continued during 13-20 July and a daily bright thermal anomaly was identified in satellite images. A new lava flow was first seen on 19 July advancing down the Apakhonchich drainage on the SE flank. The Aviation Color Code remained at Yellow (the second level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Krakatau (Indonesia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Krakatau
Sunda Volcanic Arc

PVMBG reported that daily white gas-and-steam plumes rose as high as 200 m above Krakatau’s summit during 19-25 July and drifted N, NW, W, and SW. At 0843 on 20 July dense dark gray ash plumes rose 500 m above the summit and drifted NW, followed by similar plumes during 0851-0852 that rose 2 km. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay at least 5 km away from the crater.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Lewotolok (Indonesia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Lewotolok
Sunda Volcanic Arc

PVMBG reported that the eruption at Lewotolok continued during 19-25 July. Daily dense white steam-and-gas plumes rose as high as 500 m above the summit and drifted SE, NW, W, and SW. On 21 July white-and-gray plumes rose as high as 500 m and drifted SW, W, and NW. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay at least 2 km away from the summit crater.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Merapi (Indonesia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Merapi
Sunda Volcanic Arc

BPPTKG reported that the eruption at Merapi (on Java) continued during 14-20 July and seismicity remained at elevated levels. The SW lava dome produced a total of 281 lava avalanches that descended multiple flanks; one avalanche traveled 1 km down the Sat/Putih drainage, two traveled as far as 500 m down the Senowo drainage, eight traveled a maximum distance of 2 km down the SW flank upstream from the Boyong drainage, and 270 traveled as far as 1.8 km down the Bebeng. Morphological changes to the SW lava dome were due to continuing collapses of material. The Darwin VAAC reported that multiple minor ash plumes were identified in satellite images on 19 July rising to 3.7 km (12,000 ft) a.s.l. and drifting S and SW. The emissions were more diffuse towards the end of the day and at 2350 on 19 July and 0600 on 20 July were only visible in webcam images. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit based on location.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)

Reventador (Ecuador) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Reventador
Northern Andean Volcanic Arc

IG-EPN reported that the eruption at Reventador was ongoing during 18-25 July. Seismicity was characterized by 16-40 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions. Weather clouds often hindered visual observations, though crater incandescence was visible on most nights and early mornings, and material was seen descending the flanks. Ash-and-gas plumes rose 400 m above the crater rim and drifted NW on 19 July. Crater incandescence was visible during the night of 20-21 July and incandescent blocks rolled 500 m down the flanks. An explosion at 0804 on 22 July produced a plume with moderate amounts of ash that rose 500 m above the crater rim. An explosion at 0509 on 23 July ejected incandescent material onto the flanks that descended 500 m. Ash emissions on 24 July rose less than 200 m and drifted NW. Incandescent material was ejected as far as 400 m onto the flanks. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Orange (the second highest level on a four-color scale).

Sources: Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE), Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)

Semeru (Indonesia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Semeru
Sunda Volcanic Arc

PVMBG reported that eruptive activity continued at Semeru during 19-25 July. White-and-gray ash emissions that were sometimes dense rose as high as 800 m above the summit and drifted in multiple directions during 19-20 and 22-24 July. The Alert Level remained at 3 (third highest on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km from the summit, and to avoid other drainages including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Sheveluch (Russia) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Sheveluch
Eastern Kamchatka Volcanic Arc

KVERT reported that the eruption at Sheveluch continued during 13-20 July. Intense fumarolic activity was visible at the active dome, and daily thermal anomalies were identified in satellite images. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Suwanosejima (Japan) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Suwanosejima
Ryukyu Volcanic Arc

JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 17-24 July. Multiple eruptive events during 19 and 21-24 July produced ash plumes that rose as high as 1.5 km above the crater rim. Some of the plumes drifted N and NW. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1 km away from the crater. The Alert Level remained at 2 (on a 5-level scale) and residents were warned to stay 1 km away from the crater.

Source: Japan Meteorological Agency (JMA)

Whakaari/White Island (New Zealand) | 19 July-25 July 2023 | Continuing ActivityCite this Report

Whakaari/White Island
Taupo Volcanic Zone

On 20 July GeoNet reported that continuing unrest at Whakaari/White Island was characterized by low-level gas-and-steam emissions and decreasing temperatures during the previous month. The temperatures at the large vents declined from 240 degrees Celsius in March to 120 degrees in late June. During an overflight on 18 July steam-and-gas plumes were observed rising from the same vents in the active crater area as previously observed and the discharge rates were relatively unchanged. No evidence of ash emissions or eruptive activity were observed.

After the remaining monitoring instruments on the island failed, observations were made during overflights, from the webcam located on Whakatane, and using satellite data. Significant changes in deformation or sulfur dioxide emissions were not detected in satellite data over the past few months. The Volcanic Alert Level remained at 2 (on a scale of 0-5) and the Aviation Color Code remained at Yellow (the second level on a four-color scale). GeoNet noted that the Alert Levels reflected the level of unrest at the volcano but also considered the greater level of uncertainty in activity due to the current lack of consistent and useful real-time data.

Source: GeoNet

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Criteria & Disclaimers

Criteria

The Weekly Volcanic Activity Report does not necessarily include all volcanic activity that occurred on Earth during the week. More than a dozen volcanoes globally have displayed more-or-less continuous eruptive activity for decades or longer, and such routine activity is typically not reported here. Moreover, Earth's sea-floor volcanism is seldom reported even though in theory it represents the single most prolific source of erupted material. The Weekly Volcanic Activity Report summarizes volcanic activity that meets one or more of the following criteria:

- A volcano observatory raises or lowers the alert level at the volcano.
- A volcanic ash advisory has been released by a volcanic ash advisory center (VAAC) stating that an ash cloud has been produced from the volcano.
- A verifiable news report of new activity or a change in activity at the volcano has been issued.
- Observers have reported a significant change in volcanic activity. Such activity can include, but is not restricted to, pyroclastic flows, lahars, lava flows, dome collapse, or increased unrest.

Volcanoes are included in the "New Activity/Unrest" section of the Weekly Volcanic Activity Report if the activity occurs after at least 3 months of quiescence. Once a volcano is included in the "New Activity/Unrest" section, updates will remain in that section unless the activity continues for more than 1 month without escalating, after which time updates will be listed in the "Continuing Activity" section. Volcanoes are also included in the "New Activity/Unrest" section if the volcano is undergoing a period of relatively high unrest, or increasing unrest. This is commonly equal to Alert Level Orange on a scale of Green, Yellow, Orange, Red, where Red is the highest alert. Or alert level 3 on a scale of 1-4 or 1-5.

It is important to note that volcanic activity meeting one or more of these criteria may occur during the week, but may not be included in the Weekly Volcanic Activity Report because we did not receive a report.

Disclaimers

1. The Weekly Volcanic Activity Report is intended to provide timely information about global volcanism on a weekly basis. Consequently, the report is generated rapidly by summarizing volcanic reports from various sources, with little time for fact checking. The accuracy of the Weekly Volcanic Activity Report is dependent upon the quality of the volcanic activity reports we receive. Reports published in the Bulletin of the Global Volcanism Network are cover longer time periods and are more carefully reviewed, although all of the volcanoes discussed in the Weekly Volcanic Activity Report are not necessarily reported in the Bulletin. Because of our emphasis on rapid reporting on the web we have avoided diacritical marks. Reports are updated on the Weekly Volcanic Activity Report web page as they are received, therefore information may be included regarding events that occurred before the current report period.

2. Rapidly developing events lead to coverage that is often fragmentary. Volcanoes, their eruptions, and their plumes and associated atmospheric effects are complex phenomena that may require months to years of data analysis in order to create a comprehensive summary and interpretation of events.

3. Preliminary accounts sometimes contain exaggerations and "false alarms," and accordingly, this report may include some events ultimately found to be erroneous or misleading.

4. Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.

5. USGS Disclaimer Statement for this Website:

Information presented on this website is considered public information and may be distributed or copied. Use of appropriate byline/photo/image credit is requested. We strongly recommend that USGS data be acquired directly from a USGS server and not through other sources that may change the data in some way. While USGS makes every effort to provide accurate and complete information, various data such as names, telephone numbers, etc. may change prior to updating. USGS welcomes suggestions on how to improve our home page and correct errors. USGS provides no warranty, expressed or implied, as to the accuracy, reliability or completeness of furnished data.

Some of the documents on this server may contain live references (or pointers) to information created and maintained by other organizations. Please note that USGS does not control and cannot guarantee the relevance, timeliness, or accuracy of these outside materials.

For site security purposes and to ensure that this service remains available to all users, this government computer system employs software programs to monitor network traffic to identify unauthorized attempts to upload or change information, or otherwise cause damage. Unauthorized attempts to upload information or change information on this website are strictly prohibited and may be punishable under the Computer Fraud and Abuse Act of 1986 and the National Information Infrastructure Protection Act. Information may also be used for authorized law enforcement investigations. (Last modified September 21, 1999.)

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
URL: https://volcano.si.edu/reports_weekly.cfm