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 16 August-22 August 2023
Name	Location	Eruption Start Date	Report Status
Bagana	Bougainville (Papua New Guinea)	2000 Feb 28 (in or before)	New
Dempo	Southeastern Sumatra	—	New
Shishaldin	Fox Islands (USA)	—	New
Aira	Kyushu (Japan)	2017 Mar 25	Continuing
Aniakchak	Alaska Peninsula, Alaska	—	Continuing
Ebeko	Paramushir Island (Russia)	2022 Jun 11	Continuing
Etna	Sicily (Italy)	2022 Nov 27	Continuing
Great Sitkin	Andreanof Islands (USA)	2021 May 25	Continuing
Karangetang	Sangihe Islands	2018 Nov 25	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
Nevado del Ruiz	Colombia	2014 Nov 18	Continuing
Reventador	Ecuador	2008 Jul 27	Continuing
Rincon de la Vieja	Costa Rica	2021 Jun 28	Continuing
Sabancaya	Peru	2016 Nov 6	Continuing
Sangay	Ecuador	2019 Mar 26	Continuing
Semeru	Eastern Java	2017 Jun 6	Continuing
Sheveluch	Central Kamchatka (Russia)	1999 Aug 15	Continuing
Stromboli	Aeolian Islands (Italy)	1934 Feb 2	Continuing
Suwanosejima	Ryukyu Islands (Japan)	2004 Oct 23	Continuing
Ubinas	Peru	—	Continuing

All times are local unless otherwise stated.

Bagana | 16 August-22 August 2023 | New Activity / Unrest Cite this Report

Bagana
Bougainville (Papua New Guinea)

RVO received no reports about volcanic activity at Bagana during 31 July-16 August due to the lack of information coming from the Torokina area. Photos of summit activity taken during 17-19 showed ash emissions rising no higher than 1 km above the summit and drifting SE; a small explosion produced an ash plume during the morning of 19 August. Deposits from small pyroclastic flows were also evident in the photos; lava flows and the pyroclastic-flow deposits were also identified in satellite data. Two temporary seismic stations were installed near Bagana on 17 August at distances of 7 km WSW (Vakovi station) and 11 km SW (Kepox station). The Kepox station immediately began recording continuous, low-frequency background seismicity. The Alert Level remained at Stage 2 (on a four-level scale).

Source: Rabaul Volcano Observatory (RVO)

Dempo | 16 August-22 August 2023 | New Activity / Unrest Cite this Report

Dempo
Southeastern Sumatra

PVMBG reported that an eruption at Dempo occurred at 2105 on 21 August, but no ash emissions were observed. A video posted on social media showed a Surtseyan eruption through the crater lake, with steam plumes and dark material being ejected above the lake. The Aviation Color Code was raised to Orange (the third color on a four-color scale). 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.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Tribun Sumsel

Shishaldin | 16 August-22 August 2023 | New Activity / Unrest Cite this Report

Shishaldin
Fox Islands (USA)

AVO reported that a vigorous eruption at Shishaldin on 15 August produced ash plumes that rose 9.1-11 km (30,000-36,000 ft) a.s.l. and drifted 100 km NE. Seismicity declined by 1322. An associated sulfur dioxide cloud that drifted over parts of Alaska and western Canada had mostly dissipated by 16 August, though remnants continued to be identified in satellite images at least through 18 August.

Seismicity was low during 16-22 August. Elevated surface temperatures observed daily in satellite images indicated hot material on the upper parts of the volcano. Small steam plumes with minor amounts of ash were visible in webcam images during 16-19 August. Small explosions were detected in infrasound data on the morning of 19 August and were consistent with pilot reports of small, short-lived ash plumes rising about 4.3 km (14,000 ft) a.s.l. Low-level explosive activity continued to be recorded during 20-21 August, though weather clouds sometimes prevented views; no emissions were visible in clear webcam images on the morning of 20 August. A billowing white plume was observed by an AVO field crew working nearby on 21 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)

Aira | 16 August-22 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 14-21 August. Very small eruptive events occasionally occurred at Minamidake and nighttime incandescence was observed at that same crater. A very small eruptive event was recorded at Showa on 17 August. 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)

Aniakchak | 16 August-22 August 2023 | Continuing ActivityCite this Report

Aniakchak
Alaska Peninsula, Alaska

On 17 August AVO reported that number of earthquakes beneath Aniakchak and the measurable uplift of the ground surface in the caldera had declined to background levels. The Aviation Color Code was lowered to Green (the lowest level on a four-color scale) and the Volcano Alert Level was lowered to Normal (the lowest level on a four-level scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Ebeko | 16 August-22 August 2023 | Continuing ActivityCite this Report

Ebeko
Paramushir Island (Russia)

KVERT reported that a moderate explosive activity at Ebeko was ongoing during 10-17 August. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 11-14 and 16 August generated ash plumes that rose as high as 3 km (10,000 ft) a.s.l and drifted to the S and SE. Thermal anomalies were identified in satellite images during 11 and 13-15 August; 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)

Etna | 16 August-22 August 2023 | Continuing ActivityCite this Report

Etna
Sicily (Italy)

INGV reported that an eruption at Etna began on 13 August. Tremor amplitude suddenly increased at around 2000 on 13 August and reached high values within 20 minutes. Significant infrasonic activity coincided with the tremor increase. Strombolian activity at SE Crater began to gradually intensify starting at 2040. Seismic activity continued to increase. The Aviation Color Code was raised to Yellow (second lowest level on a four-color scale) at 2126 and then to Orange at 2129 due to above-background activity. By 2333 the Strombolian activity had evolved into lava fountaining and lava overflowed the S flank of SE Crater. Ash, gas, and steam plumes drifted S and caused ashfall in areas downwind, on the volcano’s flanks and beyond. The Aviation Color Code was raised to Red at 2241 based on strong explosive activity and ashfall in Rifugio Sapienza-Piano Vetore at 1,700 m elevation on the S flank.

Seismic and infrasonic activity continued to intensify, reached a peak at around 0320 on 14 August, then rapidly decreased to pre-eruptive levels between 0450 and 0530. Coincident with the decreasing seismicity, fountaining ceased at around 0520. The Aviation Color Code was lowered to Orange as volcanic ash was confined to the summit area. Sporadic, minor ash emissions continued throughout the day. At 1415 the Aviation Color Code was lowered to Yellow and then lowered to Green at 1417. According to a news source the ash emissions caused the closure of the Catania airport, about 50 km S, from 0238 until 2000; the airport averages about 200 flights a day. Though activity decreased at the beginning of the day, ashfall continued to impact the area. The mayor banned the use of motorcycles until 16 August and banned drivers from driving over 30 kilometers per hour.

At 2346 an explosion at SE Crater produced a volcanic cloud that rapidly dispersed. The Aviation Color Code was raised to Yellow at 2355 on 14 August due to increasing unrest and lowered back to Green at 0954 on 15 August. At 2030 on 15 August a report noted that during the day the amplitude of volcanic tremor fluctuated widely and was mostly centered beneath SE Crater and E of the central craters. By 1700 infrasonic activity increased and coincided with more intense periods of tremor; the signals indicated that the source of the activity was at Bocca Nuova Crater. Gas emissions rose from both the SE and Bocca Nuova craters. The Aviation Color Code was raised to Yellow at 1944. During 15-20 August gas emissions rose from Bocca Nuova Crater and from the SE Crater’s E vent and numerous fumaroles located along the crater rim.

An 18 August satellite image was used to estimate the extent of the flow field, though the analysis was difficult due to weather clouds obscuring features in the image. The image revealed that a fissure had opened on the SW flank of SE Crater, was about 350 m long, and oriented NNE-SSW. The lava flow reached 2,790 m elevation, W of Frumento Supino, and had an estimated volume of 900,000 cubic meters and an area of 300,000 square meters.

Sources: Sezione di Catania - Osservatorio Etneo (INGV), Euronews

Great Sitkin | 16 August-22 August 2023 | Continuing ActivityCite this Report

Great Sitkin
Andreanof Islands (USA)

AVO reported that slow lava effusion likely continued at Great Sitkin during 16-22 August, producing a thick flow in the summit crater. Seismicity remained slightly elevated throughout the week. Weather clouds often obscured satellite and webcam views, though strongly elevated surface temperatures were visible during 21-22 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 | 16 August-22 August 2023 | Continuing ActivityCite this Report

Karangetang
Sangihe Islands

PVMBG reported that dense white gas-and-steam plumes from Karangetang were visible daily rising as high as 200 m and drifting multiple directions during 16-22 August. Weather clouds sometimes prevented views of the summit. A webcam images published in the reports showed incandescence at the summit and from material on the flanks of Main Crater (S crater) on 17 August. Pyroclastic flows continued to be generated by collapsing material according to a 17 August new article. 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

Klyuchevskoy | 16 August-22 August 2023 | Continuing ActivityCite this Report

Klyuchevskoy
Central Kamchatka (Russia)

KVERT reported that the explosive Strombolian eruption at Klyuchevskoy continued during 10-17 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 | 16 August-22 August 2023 | Continuing ActivityCite this Report

Lewotolok
Lembata Island

PVMBG reported that the eruption at Lewotolok continued during 16-22 August. On most days white steam-and-gas plumes rose as high as 500 m above the summit and drifted W and NW. White-and-gray ash plumes rose 100-300 m and drifted W and NW on 16 August. Incandescence at the summit was visible in a webcam image from 19 August. Possible ash plumes were visible in webcam images on most days, especially in an image from 1735 on 20 August. 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 | 16 August-22 August 2023 | Continuing ActivityCite this Report

Mayon
Luzon (Philippines)

PHIVOLCS reported that the eruption at Mayon continued during 16-22 August, with slow lava effusion from the summit crater feeding flows on the S, SE, and E flanks. The lengths of the lava flow in the Mi-Isi (S), Bonga (SE), and Basud (E) drainages remained at 2.8 km, 3.4 km, and 1.1 km, respectively. Collapses at the lava dome and from the lava flows produced incandescent rockfalls and pyroclastic density currents (PDCs, or pyroclastic flows) that descended the three drainages as far as 4 km. Each day seismic stations recorded 60-154 rockfall events and 1-7 PDC events, though no PDC events were recorded during 21-22 August. There were 23-175 volcanic earthquakes, including 4-96 tremor events, each with durations of 1-80 minutes. Sulfur dioxide emissions averaged between 753 and 4,756 tonnes per day, with the highest value recorded on 16 August. 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 | 16 August-22 August 2023 | Continuing ActivityCite this Report

Merapi
Central Java

BPPTKG reported that the eruption at Merapi (on Java) continued during 4-10 August and seismicity remained at elevated levels. The SW lava dome produced a total of 244 lava avalanches that descended the SW flank; 34 traveled as far as 1.6 km down the upper part of the Boyong drainage, 207 traveled as far as 2 km down the upper Bebeng drainage, and 3 traveled as far as 1.4 km down the Senowo drainage. 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)

Nevado del Ruiz | 16 August-22 August 2023 | Continuing ActivityCite this Report

Nevado del Ruiz
Colombia

Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that the eruption at Nevado del Ruiz continued at low levels during 15-21 August. Seismicity was generally low with occasional increases to moderate levels. Steam-and-gas emissions continued. Gas, steam, and ash plumes rose as high as 1.5 km and drifted NW and WNW on 19 August. A low-energy thermal anomaly from the crater was identified in satellite images. The Alert Level remained at Yellow, Level III (the second level on a four-level scale).

Source: Servicio Geológico Colombiano (SGC)

Reventador | 16 August-22 August 2023 | Continuing ActivityCite this Report

Reventador
Ecuador

IG-EPN reported that the eruption at Reventador was ongoing during 15-22 August. Seismicity was characterized by 21-30 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions. Crater incandescence was visible nightly and sometimes early mornings, and explosions ejected incandescent material onto the flanks. Daily ash-and-gas plumes rose 900-1,300 m above the crater rim and drifted E, NW, W, and SW during 15-21 August; weather clouds prevented views on 22 August. Secretaría de Gestión de Riesgos maintained the Alert Level at Orange (the second highest level on a four-color scale).

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Secretaría de Gestión de Riesgos (SGR)

Rincon de la Vieja | 16 August-22 August 2023 | Continuing ActivityCite this Report

Rincon de la Vieja
Costa Rica

OVSICORI-UNA reported daily small phreatic events at Rincón de la Vieja during 15-22 August. Events at 1224 on 21 August and 0749 on 22 August each produced steam-and-gas plumes that rose 500-600 m above the crater rim.

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

Sabancaya | 16 August-22 August 2023 | Continuing ActivityCite this Report

Sabancaya
Peru

Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued during 14-20 August with a daily average of 28 explosions. Gas-and-ash plumes rose as high as 3.2 km above the summit and drifted W, NW, N, and NE. A total of 13 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)

Sangay | 16 August-22 August 2023 | Continuing ActivityCite this Report

Sangay
Ecuador

IG-EPN reported a high level of eruptive activity at Sangay during 15-22 August, and seismic stations recorded 285-783 daily explosions. Crater incandescence was often visible in overnight webcam images, and during 16-18 August material on the S flank was incandescent up to 1 km from the crater. Several daily ash-and-gas plumes rose as high as 2.5 km above the crater rim and drifted mainly SW, W, and NW during 15-21 August. Ashfall was occasionally reported during 15-19 August in areas downwind, including Cebadas (35 km WNW), Guarguallá (25 km WNW), Retén (34 km WNW), and Palmira (46 km W), all located in the province of Chimborazo. Secretaría de Gestión de Riesgos maintained the Alert Level at Yellow (the second highest level on a four-color scale).

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Secretaría de Gestión de Riesgos (SGR)

Semeru | 16 August-22 August 2023 | Continuing ActivityCite this Report

Semeru
Eastern Java

PVMBG reported that eruptive activity continued at Semeru during 16-22 August. White-and-gray ash plumes rose as high as 800 m above the summit and drifted SW, W, NW, and SE during 16-17 and 19-21 August. The plumes were often dense. 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 | 16 August-22 August 2023 | Continuing ActivityCite this Report

Sheveluch
Central Kamchatka (Russia)

KVERT reported that the eruption at Sheveluch continued during 10-17 August. 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)

Stromboli | 16 August-22 August 2023 | Continuing ActivityCite this Report

Stromboli
Aeolian Islands (Italy)

INGV reported that eruptive activity continued at Stromboli during 14-20 August. Webcam images showed Strombolian activity at the summit craters in Area North (Area N) and Area Central-South (Area CS). Explosions at vents N1 and N2 in Area N were variable in intensity and ejected coarse material (bombs and lapilli) and ash. Intense spattering occurred at N1 during 17-18 August. Explosive activity in Area CS was concentrated at three vents in Sector S2. The explosions ejected bombs and lapilli, though spattering was observed during 17-18 August. Gas emissions rose from the S1 vent and the central (C) vent. The Dipartimento della Protezione Civile maintained the Alert Level at Yellow (the second highest level on a four-level scale).

Sources: Sezione di Catania - Osservatorio Etneo (INGV), Dipartimento della Protezione Civile

Suwanosejima | 16 August-22 August 2023 | Continuing ActivityCite this Report

Suwanosejima
Ryukyu Islands (Japan)

JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 14-21 August. Eruptive events at 0911 on 16 August, 1303 on 20 August, and 0317 on 21 August produced ash plumes that rose 1-1.1 km above the crater rim and drifted SE, SW, and W, respectively. 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.

Source: Japan Meteorological Agency (JMA)

Ubinas | 16 August-22 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 14-21 August. According to IGP there were a daily average of 104 volcano-tectonic earthquakes indicating rock fracturing and 71 long-period earthquakes signifying the movement of gas and magma. In addition, seismic signals associated with ash emissions were recorded for an average of eight hours per day, with a maximum of 14 hours on 17 August. According to the Buenos Aires VAAC diffuse ash-and-gas puffs rose 6.4-7.6 km (21,000-25,000 ft) a.s.l. (0.7-1.9 km above the summit) and drifted W, NW, and N during 15-18 August. IGP noted that ash-and-gas plumes rose as high as 3.5 km above the crater rim and drifted as far as 50 km W, NW, N, and NE; ash advisories were issued on 17, 18, and 21 August. Explosions were recorded at 0141 and 0918 on 21 August. 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), Buenos Aires Volcanic Ash Advisory Center (VAAC)

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
RVO received no reports about volcanic activity at Bagana during 31 July-16 August due to the lack of information coming from the Torokina area. Photos of summit activity taken during 17-19 showed ash emissions rising no higher than 1 km above the summit and drifting SE; a small explosion produced an ash plume during the morning of 19 August. Deposits from small pyroclastic flows were also evident in the photos; lava flows and the pyroclastic-flow deposits were also identified in satellite data. Two temporary seismic stations were installed near Bagana on 17 August at distances of 7 km WSW (Vakovi station) and 11 km SW (Kepox station). The Kepox station immediately began recording continuous, low-frequency background seismicity. The Alert Level remained at Stage 2 (on a four-level scale).
Source: Rabaul Volcano Observatory (RVO)

Report for Dempo
PVMBG reported that an eruption at Dempo occurred at 2105 on 21 August, but no ash emissions were observed. A video posted on social media showed a Surtseyan eruption through the crater lake, with steam plumes and dark material being ejected above the lake. The Aviation Color Code was raised to Orange (the third color on a four-color scale). 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.
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Tribun Sumsel

Report for Shishaldin
AVO reported that a vigorous eruption at Shishaldin on 15 August produced ash plumes that rose 9.1-11 km (30,000-36,000 ft) a.s.l. and drifted 100 km NE. Seismicity declined by 1322. An associated sulfur dioxide cloud that drifted over parts of Alaska and western Canada had mostly dissipated by 16 August, though remnants continued to be identified in satellite images at least through 18 August.

Seismicity was low during 16-22 August. Elevated surface temperatures observed daily in satellite images indicated hot material on the upper parts of the volcano. Small steam plumes with minor amounts of ash were visible in webcam images during 16-19 August. Small explosions were detected in infrasound data on the morning of 19 August and were consistent with pilot reports of small, short-lived ash plumes rising about 4.3 km (14,000 ft) a.s.l. Low-level explosive activity continued to be recorded during 20-21 August, though weather clouds sometimes prevented views; no emissions were visible in clear webcam images on the morning of 20 August. A billowing white plume was observed by an AVO field crew working nearby on 21 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 Aira
JMA reported ongoing activity at both Minamidake Crater and Showa Crater (Aira Caldera’s Sakurajima volcano) during 14-21 August. Very small eruptive events occasionally occurred at Minamidake and nighttime incandescence was observed at that same crater. A very small eruptive event was recorded at Showa on 17 August. 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 Aniakchak
On 17 August AVO reported that number of earthquakes beneath Aniakchak and the measurable uplift of the ground surface in the caldera had declined to background levels. The Aviation Color Code was lowered to Green (the lowest level on a four-color scale) and the Volcano Alert Level was lowered to Normal (the lowest level on a four-level scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Ebeko
KVERT reported that a moderate explosive activity at Ebeko was ongoing during 10-17 August. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 11-14 and 16 August generated ash plumes that rose as high as 3 km (10,000 ft) a.s.l and drifted to the S and SE. Thermal anomalies were identified in satellite images during 11 and 13-15 August; 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 Etna
INGV reported that an eruption at Etna began on 13 August. Tremor amplitude suddenly increased at around 2000 on 13 August and reached high values within 20 minutes. Significant infrasonic activity coincided with the tremor increase. Strombolian activity at SE Crater began to gradually intensify starting at 2040. Seismic activity continued to increase. The Aviation Color Code was raised to Yellow (second lowest level on a four-color scale) at 2126 and then to Orange at 2129 due to above-background activity. By 2333 the Strombolian activity had evolved into lava fountaining and lava overflowed the S flank of SE Crater. Ash, gas, and steam plumes drifted S and caused ashfall in areas downwind, on the volcano’s flanks and beyond. The Aviation Color Code was raised to Red at 2241 based on strong explosive activity and ashfall in Rifugio Sapienza-Piano Vetore at 1,700 m elevation on the S flank.

Seismic and infrasonic activity continued to intensify, reached a peak at around 0320 on 14 August, then rapidly decreased to pre-eruptive levels between 0450 and 0530. Coincident with the decreasing seismicity, fountaining ceased at around 0520. The Aviation Color Code was lowered to Orange as volcanic ash was confined to the summit area. Sporadic, minor ash emissions continued throughout the day. At 1415 the Aviation Color Code was lowered to Yellow and then lowered to Green at 1417. According to a news source the ash emissions caused the closure of the Catania airport, about 50 km S, from 0238 until 2000; the airport averages about 200 flights a day. Though activity decreased at the beginning of the day, ashfall continued to impact the area. The mayor banned the use of motorcycles until 16 August and banned drivers from driving over 30 kilometers per hour.

At 2346 an explosion at SE Crater produced a volcanic cloud that rapidly dispersed. The Aviation Color Code was raised to Yellow at 2355 on 14 August due to increasing unrest and lowered back to Green at 0954 on 15 August. At 2030 on 15 August a report noted that during the day the amplitude of volcanic tremor fluctuated widely and was mostly centered beneath SE Crater and E of the central craters. By 1700 infrasonic activity increased and coincided with more intense periods of tremor; the signals indicated that the source of the activity was at Bocca Nuova Crater. Gas emissions rose from both the SE and Bocca Nuova craters. The Aviation Color Code was raised to Yellow at 1944. During 15-20 August gas emissions rose from Bocca Nuova Crater and from the SE Crater’s E vent and numerous fumaroles located along the crater rim.

An 18 August satellite image was used to estimate the extent of the flow field, though the analysis was difficult due to weather clouds obscuring features in the image. The image revealed that a fissure had opened on the SW flank of SE Crater, was about 350 m long, and oriented NNE-SSW. The lava flow reached 2,790 m elevation, W of Frumento Supino, and had an estimated volume of 900,000 cubic meters and an area of 300,000 square meters.
Sources: Sezione di Catania - Osservatorio Etneo (INGV), Euronews

Report for Great Sitkin
AVO reported that slow lava effusion likely continued at Great Sitkin during 16-22 August, producing a thick flow in the summit crater. Seismicity remained slightly elevated throughout the week. Weather clouds often obscured satellite and webcam views, though strongly elevated surface temperatures were visible during 21-22 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 daily rising as high as 200 m and drifting multiple directions during 16-22 August. Weather clouds sometimes prevented views of the summit. A webcam images published in the reports showed incandescence at the summit and from material on the flanks of Main Crater (S crater) on 17 August. Pyroclastic flows continued to be generated by collapsing material according to a 17 August new article. 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

Report for Klyuchevskoy
KVERT reported that the explosive Strombolian eruption at Klyuchevskoy continued during 10-17 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 16-22 August. On most days white steam-and-gas plumes rose as high as 500 m above the summit and drifted W and NW. White-and-gray ash plumes rose 100-300 m and drifted W and NW on 16 August. Incandescence at the summit was visible in a webcam image from 19 August. Possible ash plumes were visible in webcam images on most days, especially in an image from 1735 on 20 August. 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 16-22 August, with slow lava effusion from the summit crater feeding flows on the S, SE, and E flanks. The lengths of the lava flow in the Mi-Isi (S), Bonga (SE), and Basud (E) drainages remained at 2.8 km, 3.4 km, and 1.1 km, respectively. Collapses at the lava dome and from the lava flows produced incandescent rockfalls and pyroclastic density currents (PDCs, or pyroclastic flows) that descended the three drainages as far as 4 km. Each day seismic stations recorded 60-154 rockfall events and 1-7 PDC events, though no PDC events were recorded during 21-22 August. There were 23-175 volcanic earthquakes, including 4-96 tremor events, each with durations of 1-80 minutes. Sulfur dioxide emissions averaged between 753 and 4,756 tonnes per day, with the highest value recorded on 16 August. 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 4-10 August and seismicity remained at elevated levels. The SW lava dome produced a total of 244 lava avalanches that descended the SW flank; 34 traveled as far as 1.6 km down the upper part of the Boyong drainage, 207 traveled as far as 2 km down the upper Bebeng drainage, and 3 traveled as far as 1.4 km down the Senowo drainage. 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 Nevado del Ruiz
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that the eruption at Nevado del Ruiz continued at low levels during 15-21 August. Seismicity was generally low with occasional increases to moderate levels. Steam-and-gas emissions continued. Gas, steam, and ash plumes rose as high as 1.5 km and drifted NW and WNW on 19 August. A low-energy thermal anomaly from the crater was identified in satellite images. The Alert Level remained at Yellow, Level III (the second level on a four-level scale).
Source: Servicio Geológico Colombiano (SGC)

Report for Reventador
IG-EPN reported that the eruption at Reventador was ongoing during 15-22 August. Seismicity was characterized by 21-30 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions. Crater incandescence was visible nightly and sometimes early mornings, and explosions ejected incandescent material onto the flanks. Daily ash-and-gas plumes rose 900-1,300 m above the crater rim and drifted E, NW, W, and SW during 15-21 August; weather clouds prevented views on 22 August. Secretaría de Gestión de Riesgos maintained the Alert Level at Orange (the second highest level on a four-color scale).
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Secretaría de Gestión de Riesgos (SGR)

Report for Rincon de la Vieja
OVSICORI-UNA reported daily small phreatic events at Rincón de la Vieja during 15-22 August. Events at 1224 on 21 August and 0749 on 22 August each produced steam-and-gas plumes that rose 500-600 m above the crater rim.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Report for Sabancaya
Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued during 14-20 August with a daily average of 28 explosions. Gas-and-ash plumes rose as high as 3.2 km above the summit and drifted W, NW, N, and NE. A total of 13 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 Sangay
IG-EPN reported a high level of eruptive activity at Sangay during 15-22 August, and seismic stations recorded 285-783 daily explosions. Crater incandescence was often visible in overnight webcam images, and during 16-18 August material on the S flank was incandescent up to 1 km from the crater. Several daily ash-and-gas plumes rose as high as 2.5 km above the crater rim and drifted mainly SW, W, and NW during 15-21 August. Ashfall was occasionally reported during 15-19 August in areas downwind, including Cebadas (35 km WNW), Guarguallá (25 km WNW), Retén (34 km WNW), and Palmira (46 km W), all located in the province of Chimborazo. Secretaría de Gestión de Riesgos maintained the Alert Level at Yellow (the second highest level on a four-color scale).
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Secretaría de Gestión de Riesgos (SGR)

Report for Semeru
PVMBG reported that eruptive activity continued at Semeru during 16-22 August. White-and-gray ash plumes rose as high as 800 m above the summit and drifted SW, W, NW, and SE during 16-17 and 19-21 August. The plumes were often dense. 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 Sheveluch
KVERT reported that the eruption at Sheveluch continued during 10-17 August. 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)

Report for Stromboli
INGV reported that eruptive activity continued at Stromboli during 14-20 August. Webcam images showed Strombolian activity at the summit craters in Area North (Area N) and Area Central-South (Area CS). Explosions at vents N1 and N2 in Area N were variable in intensity and ejected coarse material (bombs and lapilli) and ash. Intense spattering occurred at N1 during 17-18 August. Explosive activity in Area CS was concentrated at three vents in Sector S2. The explosions ejected bombs and lapilli, though spattering was observed during 17-18 August. Gas emissions rose from the S1 vent and the central (C) vent. The Dipartimento della Protezione Civile maintained the Alert Level at Yellow (the second highest level on a four-level scale).
Sources: Sezione di Catania - Osservatorio Etneo (INGV), Dipartimento della Protezione Civile

Report for Suwanosejima
JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 14-21 August. Eruptive events at 0911 on 16 August, 1303 on 20 August, and 0317 on 21 August produced ash plumes that rose 1-1.1 km above the crater rim and drifted SE, SW, and W, respectively. 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.
Source: Japan Meteorological Agency (JMA)

Report for Ubinas
Instituto Geofísico del Perú (IGP) and Instituto Geológico Minero y Metalúrgico (INGEMMET) reported that the eruption at Ubinas continued during 14-21 August. According to IGP there were a daily average of 104 volcano-tectonic earthquakes indicating rock fracturing and 71 long-period earthquakes signifying the movement of gas and magma. In addition, seismic signals associated with ash emissions were recorded for an average of eight hours per day, with a maximum of 14 hours on 17 August. According to the Buenos Aires VAAC diffuse ash-and-gas puffs rose 6.4-7.6 km (21,000-25,000 ft) a.s.l. (0.7-1.9 km above the summit) and drifted W, NW, and N during 15-18 August. IGP noted that ash-and-gas plumes rose as high as 3.5 km above the crater rim and drifted as far as 50 km W, NW, N, and NE; ash advisories were issued on 17, 18, and 21 August. Explosions were recorded at 0141 and 0918 on 21 August. 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), Buenos Aires Volcanic Ash Advisory Center (VAAC)