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 2 August-8 August 2023
Name	Location	Eruption Start Date	Report Status
Bagana	Bougainville (Papua New Guinea)	2000 Feb 28 (in or before)	New
Poas	Costa Rica	2023 Dec 1	New
Shishaldin	Fox Islands (USA)	—	New
Ulawun	New Britain (Papua New Guinea)	—	New
Aira	Kyushu (Japan)	2017 Mar 25	Continuing
Dukono	Halmahera	1933 Aug 13	Continuing
Ebeko	Paramushir Island (Russia)	2022 Jun 11	Continuing
Fagradalsfjall	Iceland	—	Continuing
Great Sitkin	Andreanof Islands (USA)	2021 May 25	Continuing
Karangetang	Sangihe Islands	2018 Nov 25	Continuing
Katmai	Alaska	—	Continuing
Klyuchevskoy	Central Kamchatka (Russia)	—	Continuing
Lewotolok	Lembata Island	2020 Nov 27	Continuing
Mayon	Luzon (Philippines)	2023 Apr 27 ± 2 days	Continuing
Merapi	Central Java	2020 Dec 31	Continuing
Piton de la Fournaise	Reunion Island (France)	—	Continuing
Sabancaya	Peru	2016 Nov 6	Continuing
Semeru	Eastern Java	2017 Jun 6	Continuing
Semisopochnoi	Aleutian Islands (USA)	—	Continuing
Sheveluch	Central Kamchatka (Russia)	1999 Aug 15	Continuing
Ubinas	Peru	—	Continuing

All times are local unless otherwise stated.

Bagana | 2 August-8 August 2023 | New Activity / Unrest Cite this Report

Bagana
Bougainville (Papua New Guinea)

The Darwin VAAC reported that an intense thermal anomaly over Bagana was identified in satellite images during 30-31 July. Ash emissions rose to 2.4 km (8,000 ft) a.s.l. and drifted WSW on 30 July. The VAAC received a ground report from RVO describing localized emissions at 0900 on 31 July. Ash was not identified in satellite images, though weather clouds obscured views.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Poas | 2 August-8 August 2023 | New Activity / Unrest Cite this Report

Poas
Costa Rica

OVSICORI-UNA reported that a small phreatic eruption at Poás occurred at 0153 on 2 August at the W part of the crater lake, ejecting material about 20 m above the water. At 1655 on 5 August a phreatic eruption from three areas of the lake ejected sediment and steam 50-100 m above the lake. At least two eruptive pulses were seen. Fumarolic degassing and lake convection were visible during 2-8 August.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Shishaldin | 2 August-8 August 2023 | New Activity / Unrest Cite this Report

Shishaldin
Fox Islands (USA)

AVO reported that the effusive and explosive eruption at Shishaldin continued during 1-8 August. Low-level ash emissions rose to below 3 km (10,000 ft) a.s.l. and drifted over 90 km N during 1-2 August. Seismicity was low but punctuated by a few episodes of volcanic tremor associated with the ash emissions. Elevated surface temperatures were consistent with cooling lava over a few days but had begun to increase and were visible though moderate weather cloud cover during 2-3 August; the increasing temperatures were consistent with lava effusion. Seismic tremor began to steadily increase at around 1036 on 3 August. Explosive activity about 20 hours later was detected using infrasound and seismic data. An ash cloud was visible in a satellite image at 0520 on 4 August rising to 7.6 km (25,000 ft) a.s.l. and drifting 60-75 km NE. Pilots saw and reported the plume at 0836. By 0900 the plume had risen to 9 km (30,000 ft) a.s.l., prompting AVO to raise the Aviation Color Code to Red (the highest color on a four-color scale) and the Volcano Alert Level to Warning (the highest level on a four-level scale) at 1017. The National Weather Service issued a Significant Meteorological Information (SIGMET) statement for the ash cloud and a Special Weather Statement warned of possible trace amounts of ash on marine waters downwind of Shishaldin. Seismic tremor levels peaked at 1400 and then sharply declined at 1500 to slightly elevated levels; the plume was sustained during the period of high tremor and drifted N and NE. AVO lowered the Volcano Alert Level to Watch and the Aviation Color Code to Orange at 1955. Seismic tremor levels were low. Ash emissions were possibly continuing but they could not be confirmed due to meteorological clouds cover. Elevated surface temperatures observed in satellite data during 5-8 August were consistent with cooling lava. Seismicity has remained low with a few daily local earthquakes.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Ulawun | 2 August-8 August 2023 | New Activity / Unrest Cite this Report

Ulawun
New Britain (Papua New Guinea)

Rabaul Volcano Observatory (RVO) reported that small, diffuse, white plumes rose from Ulawun’s summit during 27 July-4 August when there were extended periods of good visibility from the webcam in Ulamona (11-12 km NW). Seismicity fluctuated at moderate levels and was dominated by volcanic tremor; RSAM values ranged from 380 to 800. The Alert Level was lowered to Stage 1 (the lowest level on the four-level scale) on 31 July. Overall, RSAM showed a slow and erratic upward trend during 15 July-4 August and corresponded to an increase in volcanic tremor amplitudes. RVO warned that minor eruptive activity may occur if the trend continued and that ash emissions had previously occurred at similar RSAM levels.

Source: Rabaul Volcano Observatory (RVO)

Aira | 2 August-8 August 2023 | Continuing ActivityCite this Report

Aira
Kyushu (Japan)

JMA reported ongoing activity at both Minamidake Crater and Showa Crater (Aira Caldera’s Sakurajima volcano) during 31 July-7 August. Nighttime incandescence at Minamidake was occasionally observed. Sulfur dioxide emissions measured during a field visit on 3 August averaged 1,800 tons per day. An eruptive event at Showa at 0542 on 4 August produced an ash plume that rose 1 km above the crater rim and drifted N, and ejected blocks 400 m from the crater. An explosion at the same crater at 2150 produced an ash plume that rose 2.3 km above the crater rim and drifted NW, and ejected blocks as far as 800 m from the vent. 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)

Dukono | 2 August-8 August 2023 | Continuing ActivityCite this Report

Dukono
Halmahera

PVMBG reported that the eruption at Dukono was ongoing during 2-8 August. Dense white-and-gray plumes rose as high as 450 m above the summit and drifted in multiple directions on all days except 3 August when only white plumes were reported. The Alert Level remained at Level 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

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

Ebeko | 2 August-8 August 2023 | Continuing ActivityCite this Report

Ebeko
Paramushir Island (Russia)

KVERT reported that moderate explosive activity at Ebeko was ongoing during 27 July-3 August. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 27 July and 2-3 August generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l and drifted to the NE and SE. Thermal anomalies were identified in satellite images on 29 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)

Fagradalsfjall | 2 August-8 August 2023 | Continuing ActivityCite this Report

Fagradalsfjall
Iceland

At 1706 on 5 August IMO lowered the Aviation Color Code for Fagradalsfjall to Yellow (the second level on a four-color scale), noting that the eruption had declined during the previous few days and very minor activity at the crater was visible in webcam images. Tremor had decreased during the previous 36 hours and reached background levels by 1500 on 5 August. Gas plumes had typically risen 1-2 km above the vent, though on 1 August plumes rose more than 2.5 km, and according to news articles, a notable amount of fume rose from the vent on 4 August. The crater had become deeper and smaller by 4 August. Activity was last seen on 5 August and a thermal anomaly in the crater was last identified in satellite images on 6 August.

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

Great Sitkin | 2 August-8 August 2023 | Continuing ActivityCite this Report

Great Sitkin
Andreanof Islands (USA)

AVO reported that slow lava effusion continued at Great Sitkin during 1-8 August, producing a thick flow in the summit crater. The eastern lobe continued to advance into glacial ice surrounding the crater, causing the ice to deform and crack, based on a 1 August satellite image. Seismicity remained slightly elevated throughout the week. Weather clouds often obscured satellite and webcam views, though a clear image showed no unusual activity during 5-6 August and an image showed diffuse steaming from the lava surface during 6-7 August. 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)

Karangetang | 2 August-8 August 2023 | Continuing ActivityCite this Report

Karangetang
Sangihe Islands

PVMBG reported that dense white gas-and-steam plumes from Karangetang were visible rising as high as 250 m and drifting multiple directions on most days during 2-8 August. Webcam images published in the reports showed incandescence at the summit and from material on the flanks of Main Crater (S crater). According to a news source, lava avalanches traveled more than 1-1.5 km SW down the Batang, Timbelang, and West Beha drainages. Lava flows in drainages on the S and SW flanks were active; the flow in the Batuawang was 1.5 km long, the flow in Kahetang was more than 1.8 km long, and the flow in Keting was 2.1 km long. Gray clouds sometimes accompanied lava flow activity. Incandescent material was sometimes ejected up to 25 m above the summit. During the end of the week 104 people were evacuated from the Tatahadeng and Tarorane villages, located within a 2.5-km radius of the crater, to evacuation centers and remained there at least through 9 August. Incandescence at the dome in the N crater continued to be visible. 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), Antara News, Antara News, Antara News

Katmai | 2 August-8 August 2023 | Continuing ActivityCite this Report

Katmai
Alaska

AVO reported that beginning at about 1430 on 4 August, strong SE winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes dispersed unconsolidated ash up to 1.8 km (6,000 ft) a.s.l. to the NW. The ash was originally deposited during the Novarupta-Katmai eruption in 1912. The Volcano Alert Level remained at Normal (the lowest level on a four-level scale) and the Aviation Color Code remained at Green (the lowest level on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Klyuchevskoy | 2 August-8 August 2023 | Continuing ActivityCite this Report

Klyuchevskoy
Central Kamchatka (Russia)

KVERT reported that the explosive Strombolian eruption at Klyuchevskoy continued during 28 July-3 August and a daily bright thermal anomaly was identified in satellite images. Lava advanced 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)

Lewotolok | 2 August-8 August 2023 | Continuing ActivityCite this Report

Lewotolok
Lembata Island

PVMBG reported that the eruption at Lewotolok continued during 2-8 August. Daily white steam-and-gas plumes rose as high as 400 m above the summit and drifted W and NW. On 7 August white-and-gray plumes rose as high as 200 m and drifted W and NW. Incandescent material being ejected above the summit was visible in a few of the webcam images posted during the week. 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)

Mayon | 2 August-8 August 2023 | Continuing ActivityCite this Report

Mayon
Luzon (Philippines)

PHIVOLCS reported that the eruption at Mayon continued during 2-8 August, with slow lava effusion from the summit crater feeding 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, the flow in the Basud (E) drainage remained at 600 m long, and the flow in the Bonga (SE) drainage was 3.4 km 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. Each day seismic stations recorded 66-225 rockfall events, 1-9 PDC events, and 44-272 low-frequency volcanic earthquakes. Sulfur dioxide emissions were reported on most days, averaging between 969 and 3,465 tonnes per day, with the highest value recorded on 2 August. There was a total of 27 emissions of short, dark ash plumes (called “ashing” by PHIVOLCS) during 1-4 August. Daily seismicity during 3-8 August included 10-197 tremor events, each with durations of 1-18 minutes. A short-lived (35 seconds) ejection of lava at 0442 on 6 August was accompanied by seismic and infrasound signals. 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.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Merapi | 2 August-8 August 2023 | Continuing ActivityCite this Report

Merapi
Central Java

BPPTKG reported that the eruption at Merapi (on Java) continued during 28 July-3 August and seismicity remained at elevated levels. The SW lava dome produced a total of 194 lava avalanches that descended the SW flank; 12 traveled as far as 1.6 km down the upper part of the Boyong drainage and 182 traveled as far as 2 km down the upper Bebeng drainage. One earthquake signal indicating a pyroclastic flow was recorded by the seismic network. Morphological changes to the SW lava dome were due to continuing collapses of material. 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)

Piton de la Fournaise | 2 August-8 August 2023 | Continuing ActivityCite this Report

Piton de la Fournaise
Reunion Island (France)

OVPF reported that the eruption at Piton de la Fournaise was ongoing during 1-8 August, though weather conditions often obscured views. The amplitude of volcanic tremor (an indicator of lava and gas emissions) was relatively stable during the week. The active cone located on the upper part of Grandes Pentes, SE of Enclos Fouqué, at approximately 1,720 m a.s.l. continued to produce minor spattering. Lava flows traveled mainly through tubes but incandescence from breakout flows were occasionally visible in semi-clear views; flows were visibly active 1.2-2 km from the cone during 2-3 August. The Alert Level remained at 2-1, signifying an “ongoing eruption” inside the Enclos Fouqué caldera.

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

Sabancaya | 2 August-8 August 2023 | Continuing ActivityCite this Report

Sabancaya
Peru

Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued during 31 July-6 August with a daily average of 19 explosions. Gas-and-ash plumes rose as high as 2.3 km above the summit and drifted in multiple directions. Three thermal anomalies from the lava dome in the summit crater were detected using satellite data. Minor inflation was detected near the Hualca Hualca sector (4 km N). The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12 km radius.

Source: Instituto Geofísico del Perú (IGP)

Semeru | 2 August-8 August 2023 | Continuing ActivityCite this Report

Semeru
Eastern Java

PVMBG reported that eruptive activity continued at Semeru during 2-8 August. White-and-gray or gray-to-brown ash plumes that were sometimes dense rose as high as 1 km above the summit and drifted in multiple directions during 2-3, 5, and 7-8 August. 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)

Semisopochnoi | 2 August-8 August 2023 | Continuing ActivityCite this Report

Semisopochnoi
Aleutian Islands (USA)

AVO reported that the last time possible explosions were detected at Semisopochnoi’s Mount Young in monitoring data was 25 April and the last ash emission occurred on 5 May. Since then, earthquake activity has been low and steaming from the N crater continued. On 3 August the Volcano Alert Level was lowered to Normal (the lowest level on a four-level scale) and the Aviation Color Code was lowered to Green (the lowest color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Sheveluch | 2 August-8 August 2023 | Continuing ActivityCite this Report

Sheveluch
Central Kamchatka (Russia)

KVERT reported that the eruption at Sheveluch continued during 27 July-3 August. Intense fumarolic activity was visible at the active dome, and daily thermal anomalies were identified in satellite images. An ash plume was visible in satellite images drifting 82 km E on 28 July. 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)

Ubinas | 2 August-8 August 2023 | Continuing ActivityCite this Report

Ubinas
Peru

Instituto Geofísico del Perú (IGP) and Instituto Geológico Minero y Metalúrgico (INGEMMET) reported that the eruption at Ubinas continued during 31 July-7 August. According to IGP a daily average of 115 volcano-tectonic earthquakes indicating rock fracturing and 124 long-period earthquakes signifying the movement of gas and magma 31 July-6 August. In addition, there were four seismic signals associated with explosive events (mainly on 1 and 6 August) and 6-9 daily hours of seismic signals related to ash emissions. At 2110 on 1 August a major explosion produced an ash plume that rose as high as 5.4 km above the crater rim and ejected blocks as far as 3 km from the crater onto the SW, S, and SE flanks. The ash plume drifted 30 km E, SE, S, SW, and W, causing ashfall in the districts of Ubinas (6 km SE) and Chojata (19 km ESE). Ash-and-gas emissions rose as high as 2 km and drifted in multiple directions on the other days of the week. Ashfall was reported within a 15-km radius. An explosion at 0009 on 6 August produced a gas-and-ash plume that rose 1.4 km and drifted SE and E, causing ashfall in Ubinas and Chojata and other areas within a 30-km radius. INGEMMET noted that sulfur dioxide emissions were low on 7 August, averaging 400 tons per day. 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)

Weekly Reports Archive

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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.

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Acronyms and Abbreviations

a.s.l. - above sea level

AVO - Alaska Volcano Observatory

AVHRR - Advanced Very High Resolution Radiometer

CENAPRED - Centro Nacionale de Prevencion de Desastres (México)

CONRED - Coordinadora Nacional para la Reducción de Desastres

COSPEC - Correlation Spectrometer

CVGHM (formerly VSI) - Center of Volcanology and Geological Hazard Mitigation

CVO - Cascades Volcano Observatory (USGS)

GMS - Geostationary Meteorological Satellite

GOES - Geostationary Operational Environmental Satellite

GVO - Goma Volcano Observatory

GVP - Global Volcanism Program (Smithsonian Institution)

HVO - Hawaiian Volcano Observatory (USGS)

ICE - Instituto Costarricense de Electricidad (Costa Rica)

IG - Instituto Geofísico (Ecuador)

IGNS - Institute of Geological and Nuclear Sciences (New Zealand) - now GNS Science

INETER - Instituto Nicaragüense de Estudios Territoriales (Nicaragua)

INGEMMET - Instituto Geológical Minero y Metalúrgico (Peru)

INGEOMINAS - Instituto Colombiano de Geología y Minería (Colombia)

INGV-CT - Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (Italy)

INSIVUMEH - Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia (Guatemala)

IRD - Institut de Recherche pour le Développement (France)

JMA - Japanese Meteorological Agency

KEMSD - Kamchatkan Experimental and Methodical Seismilogical Department

KVERT - Kamchatkan Volcanic Eruption Response Team

M - magnitude

METEOSAT - Meteorological Satellite

MEVO - Mount Erebus Volcano Observatory

MODIS - Moderate Resolution Imaging Spectroradiometer

MVO - Montserrat Volcano Observatory

MWO - Meteorological Watch Office

NEIC - National Earthquake Information Center

NIED - National Research Institute for Earth Science and Disaster Prevention (Japan)

NOAA - National Oceanic and Atmospheric Administration

NOTAM - Notice to Airmen

OVDAS - Observatorio Volcanologico de los Andes del Sur (Chile)

OFDA - Office of US Foreign Disaster Assistance

ONEMI - Oficina Nacional de Emergencia - Ministerio del Interior (Chile)

OVPDLF - Observatoire Volcanologique du Piton de la Fournaise (France)

OVSICORI-UNA - Observatorio Vulcanologico y Sismologico de Costa Rica, Universidad Nacional (Costa Rica)

PHIVOLCS - Philippine Institute of Volcanology and Seismology (Philippines)

RSAM - Real-time Seismic Amplitude Measurement

RVO - Rabaul Volcano Observatory

SERNAGEOMIN - Servicio Nacional de Geologia y Mineria (Chile)

SIGMET - Significant Meteorological Information

SNET - Servicio Nacional de Estudios Territoriales (El Salvador)

SVERT - Sakhalin Volcanic Eruption Response Team (Russia)

USAID - US Agency for International Development

USGS - United States Geological Survey

UTC - Coordinated Universal Time

VAAC - Volcanic Ash Advisory Center

VAFTAD - Volcanic Ash Forecast Transport And Dispersion

VDAP - Volcano Disaster Assistance Program (USGS)

VHP - Volcano Hazards Program (USGS)

VRC - Volcano Research Center (Japan)

Report for Bagana
The Darwin VAAC reported that an intense thermal anomaly over Bagana was identified in satellite images during 30-31 July. Ash emissions rose to 2.4 km (8,000 ft) a.s.l. and drifted WSW on 30 July. The VAAC received a ground report from RVO describing localized emissions at 0900 on 31 July. Ash was not identified in satellite images, though weather clouds obscured views.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Report for Poas
OVSICORI-UNA reported that a small phreatic eruption at Poás occurred at 0153 on 2 August at the W part of the crater lake, ejecting material about 20 m above the water. At 1655 on 5 August a phreatic eruption from three areas of the lake ejected sediment and steam 50-100 m above the lake. At least two eruptive pulses were seen. Fumarolic degassing and lake convection were visible during 2-8 August.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Report for Shishaldin
AVO reported that the effusive and explosive eruption at Shishaldin continued during 1-8 August. Low-level ash emissions rose to below 3 km (10,000 ft) a.s.l. and drifted over 90 km N during 1-2 August. Seismicity was low but punctuated by a few episodes of volcanic tremor associated with the ash emissions. Elevated surface temperatures were consistent with cooling lava over a few days but had begun to increase and were visible though moderate weather cloud cover during 2-3 August; the increasing temperatures were consistent with lava effusion. Seismic tremor began to steadily increase at around 1036 on 3 August. Explosive activity about 20 hours later was detected using infrasound and seismic data. An ash cloud was visible in a satellite image at 0520 on 4 August rising to 7.6 km (25,000 ft) a.s.l. and drifting 60-75 km NE. Pilots saw and reported the plume at 0836. By 0900 the plume had risen to 9 km (30,000 ft) a.s.l., prompting AVO to raise the Aviation Color Code to Red (the highest color on a four-color scale) and the Volcano Alert Level to Warning (the highest level on a four-level scale) at 1017. The National Weather Service issued a Significant Meteorological Information (SIGMET) statement for the ash cloud and a Special Weather Statement warned of possible trace amounts of ash on marine waters downwind of Shishaldin. Seismic tremor levels peaked at 1400 and then sharply declined at 1500 to slightly elevated levels; the plume was sustained during the period of high tremor and drifted N and NE. AVO lowered the Volcano Alert Level to Watch and the Aviation Color Code to Orange at 1955. Seismic tremor levels were low. Ash emissions were possibly continuing but they could not be confirmed due to meteorological clouds cover. Elevated surface temperatures observed in satellite data during 5-8 August were consistent with cooling lava. Seismicity has remained low with a few daily local earthquakes.
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Ulawun
Rabaul Volcano Observatory (RVO) reported that small, diffuse, white plumes rose from Ulawun’s summit during 27 July-4 August when there were extended periods of good visibility from the webcam in Ulamona (11-12 km NW). Seismicity fluctuated at moderate levels and was dominated by volcanic tremor; RSAM values ranged from 380 to 800. The Alert Level was lowered to Stage 1 (the lowest level on the four-level scale) on 31 July. Overall, RSAM showed a slow and erratic upward trend during 15 July-4 August and corresponded to an increase in volcanic tremor amplitudes. RVO warned that minor eruptive activity may occur if the trend continued and that ash emissions had previously occurred at similar RSAM levels.
Source: Rabaul Volcano Observatory (RVO)

Report for Aira
JMA reported ongoing activity at both Minamidake Crater and Showa Crater (Aira Caldera’s Sakurajima volcano) during 31 July-7 August. Nighttime incandescence at Minamidake was occasionally observed. Sulfur dioxide emissions measured during a field visit on 3 August averaged 1,800 tons per day. An eruptive event at Showa at 0542 on 4 August produced an ash plume that rose 1 km above the crater rim and drifted N, and ejected blocks 400 m from the crater. An explosion at the same crater at 2150 produced an ash plume that rose 2.3 km above the crater rim and drifted NW, and ejected blocks as far as 800 m from the vent. 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)

Report for Dukono
PVMBG reported that the eruption at Dukono was ongoing during 2-8 August. Dense white-and-gray plumes rose as high as 450 m above the summit and drifted in multiple directions on all days except 3 August when only white plumes were reported. The Alert Level remained at Level 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Ebeko
KVERT reported that moderate explosive activity at Ebeko was ongoing during 27 July-3 August. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 27 July and 2-3 August generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l and drifted to the NE and SE. Thermal anomalies were identified in satellite images on 29 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)

Report for Fagradalsfjall
At 1706 on 5 August IMO lowered the Aviation Color Code for Fagradalsfjall to Yellow (the second level on a four-color scale), noting that the eruption had declined during the previous few days and very minor activity at the crater was visible in webcam images. Tremor had decreased during the previous 36 hours and reached background levels by 1500 on 5 August. Gas plumes had typically risen 1-2 km above the vent, though on 1 August plumes rose more than 2.5 km, and according to news articles, a notable amount of fume rose from the vent on 4 August. The crater had become deeper and smaller by 4 August. Activity was last seen on 5 August and a thermal anomaly in the crater was last identified in satellite images on 6 August.
Sources: Icelandic Meteorological Office (IMO), Icelandic National Broadcasting Service (RUV), Icelandic National Broadcasting Service (RUV)

Report for Great Sitkin
AVO reported that slow lava effusion continued at Great Sitkin during 1-8 August, producing a thick flow in the summit crater. The eastern lobe continued to advance into glacial ice surrounding the crater, causing the ice to deform and crack, based on a 1 August satellite image. Seismicity remained slightly elevated throughout the week. Weather clouds often obscured satellite and webcam views, though a clear image showed no unusual activity during 5-6 August and an image showed diffuse steaming from the lava surface during 6-7 August. 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)

Report for Karangetang
PVMBG reported that dense white gas-and-steam plumes from Karangetang were visible rising as high as 250 m and drifting multiple directions on most days during 2-8 August. Webcam images published in the reports showed incandescence at the summit and from material on the flanks of Main Crater (S crater). According to a news source, lava avalanches traveled more than 1-1.5 km SW down the Batang, Timbelang, and West Beha drainages. Lava flows in drainages on the S and SW flanks were active; the flow in the Batuawang was 1.5 km long, the flow in Kahetang was more than 1.8 km long, and the flow in Keting was 2.1 km long. Gray clouds sometimes accompanied lava flow activity. Incandescent material was sometimes ejected up to 25 m above the summit. During the end of the week 104 people were evacuated from the Tatahadeng and Tarorane villages, located within a 2.5-km radius of the crater, to evacuation centers and remained there at least through 9 August. Incandescence at the dome in the N crater continued to be visible. 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), Antara News, Antara News, Antara News

Report for Katmai
AVO reported that beginning at about 1430 on 4 August, strong SE winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes dispersed unconsolidated ash up to 1.8 km (6,000 ft) a.s.l. to the NW. The ash was originally deposited during the Novarupta-Katmai eruption in 1912. The Volcano Alert Level remained at Normal (the lowest level on a four-level scale) and the Aviation Color Code remained at Green (the lowest level on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Klyuchevskoy
KVERT reported that the explosive Strombolian eruption at Klyuchevskoy continued during 28 July-3 August and a daily bright thermal anomaly was identified in satellite images. Lava advanced 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)

Report for Lewotolok
PVMBG reported that the eruption at Lewotolok continued during 2-8 August. Daily white steam-and-gas plumes rose as high as 400 m above the summit and drifted W and NW. On 7 August white-and-gray plumes rose as high as 200 m and drifted W and NW. Incandescent material being ejected above the summit was visible in a few of the webcam images posted during the week. 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)

Report for Mayon
PHIVOLCS reported that the eruption at Mayon continued during 2-8 August, with slow lava effusion from the summit crater feeding 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, the flow in the Basud (E) drainage remained at 600 m long, and the flow in the Bonga (SE) drainage was 3.4 km 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. Each day seismic stations recorded 66-225 rockfall events, 1-9 PDC events, and 44-272 low-frequency volcanic earthquakes. Sulfur dioxide emissions were reported on most days, averaging between 969 and 3,465 tonnes per day, with the highest value recorded on 2 August. There was a total of 27 emissions of short, dark ash plumes (called “ashing” by PHIVOLCS) during 1-4 August. Daily seismicity during 3-8 August included 10-197 tremor events, each with durations of 1-18 minutes. A short-lived (35 seconds) ejection of lava at 0442 on 6 August was accompanied by seismic and infrasound signals. 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.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Report for Merapi
BPPTKG reported that the eruption at Merapi (on Java) continued during 28 July-3 August and seismicity remained at elevated levels. The SW lava dome produced a total of 194 lava avalanches that descended the SW flank; 12 traveled as far as 1.6 km down the upper part of the Boyong drainage and 182 traveled as far as 2 km down the upper Bebeng drainage. One earthquake signal indicating a pyroclastic flow was recorded by the seismic network. Morphological changes to the SW lava dome were due to continuing collapses of material. 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)

Report for Piton de la Fournaise
OVPF reported that the eruption at Piton de la Fournaise was ongoing during 1-8 August, though weather conditions often obscured views. The amplitude of volcanic tremor (an indicator of lava and gas emissions) was relatively stable during the week. The active cone located on the upper part of Grandes Pentes, SE of Enclos Fouqué, at approximately 1,720 m a.s.l. continued to produce minor spattering. Lava flows traveled mainly through tubes but incandescence from breakout flows were occasionally visible in semi-clear views; flows were visibly active 1.2-2 km from the cone during 2-3 August. The Alert Level remained at 2-1, signifying an “ongoing eruption” inside the Enclos Fouqué caldera.
Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)

Report for Sabancaya
Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued during 31 July-6 August with a daily average of 19 explosions. Gas-and-ash plumes rose as high as 2.3 km above the summit and drifted in multiple directions. Three thermal anomalies from the lava dome in the summit crater were detected using satellite data. Minor inflation was detected near the Hualca Hualca sector (4 km N). The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12 km radius.
Source: Instituto Geofísico del Perú (IGP)

Report for Semeru
PVMBG reported that eruptive activity continued at Semeru during 2-8 August. White-and-gray or gray-to-brown ash plumes that were sometimes dense rose as high as 1 km above the summit and drifted in multiple directions during 2-3, 5, and 7-8 August. 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)

Report for Semisopochnoi
AVO reported that the last time possible explosions were detected at Semisopochnoi’s Mount Young in monitoring data was 25 April and the last ash emission occurred on 5 May. Since then, earthquake activity has been low and steaming from the N crater continued. On 3 August the Volcano Alert Level was lowered to Normal (the lowest level on a four-level scale) and the Aviation Color Code was lowered to Green (the lowest color on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Sheveluch
KVERT reported that the eruption at Sheveluch continued during 27 July-3 August. Intense fumarolic activity was visible at the active dome, and daily thermal anomalies were identified in satellite images. An ash plume was visible in satellite images drifting 82 km E on 28 July. 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)

Report for Ubinas
Instituto Geofísico del Perú (IGP) and Instituto Geológico Minero y Metalúrgico (INGEMMET) reported that the eruption at Ubinas continued during 31 July-7 August. According to IGP a daily average of 115 volcano-tectonic earthquakes indicating rock fracturing and 124 long-period earthquakes signifying the movement of gas and magma 31 July-6 August. In addition, there were four seismic signals associated with explosive events (mainly on 1 and 6 August) and 6-9 daily hours of seismic signals related to ash emissions. At 2110 on 1 August a major explosion produced an ash plume that rose as high as 5.4 km above the crater rim and ejected blocks as far as 3 km from the crater onto the SW, S, and SE flanks. The ash plume drifted 30 km E, SE, S, SW, and W, causing ashfall in the districts of Ubinas (6 km SE) and Chojata (19 km ESE). Ash-and-gas emissions rose as high as 2 km and drifted in multiple directions on the other days of the week. Ashfall was reported within a 15-km radius. An explosion at 0009 on 6 August produced a gas-and-ash plume that rose 1.4 km and drifted SE and E, causing ashfall in Ubinas and Chojata and other areas within a 30-km radius. INGEMMET noted that sulfur dioxide emissions were low on 7 August, averaging 400 tons per day. 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)