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 10 May-16 May 2023
Name	Location	Eruption Start Date	Report Status
Fuego	South-Central Guatemala	2002 Jan 4	New
Kita-Ioto	Volcano Islands (Japan)	—	New
Aira	Kyushu (Japan)	2017 Mar 25	Continuing
Bezymianny	Central Kamchatka (Russia)	2016 Dec 5	Continuing
Cotopaxi	Ecuador	—	Continuing
Dukono	Halmahera	1933 Aug 13	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
Krakatau	Sunda Strait	—	Continuing
Lewotolok	Lembata Island	2020 Nov 27	Continuing
Merapi	Central Java	2020 Dec 31	Continuing
Nyamulagira	DR Congo	2018 Apr 18	Continuing
Popocatepetl	Mexico	2005 Jan 9	Continuing
Reventador	Ecuador	2008 Jul 27	Continuing
Rincon de la Vieja	Costa Rica	2021 Jun 28	Continuing
Sangay	Ecuador	2019 Mar 26	Continuing
Santa Maria	Southwestern Guatemala	1922 Jun 22	Continuing
Semeru	Eastern Java	2017 Jun 6	Continuing
Semisopochnoi	Aleutian Islands (USA)	—	Continuing
Sheveluch	Central Kamchatka (Russia)	1999 Aug 15	Continuing
St. Helens	Washington	—	Continuing
Stromboli	Aeolian Islands (Italy)	1934 Feb 2	Continuing
Suwanosejima	Ryukyu Islands (Japan)	2004 Oct 23	Continuing

All times are local unless otherwise stated.

Fuego | 10 May-16 May 2023 | New Activity / Unrest Cite this Report

Fuego
South-Central Guatemala

INSIVUMEH reported that a range of 1-7 weak explosions per hour were recorded at Fuego during 10-16 May. The explosions generated ash plumes that rose to a maximum height of 850 m above the crater and drifted up to 12 km E, SE, S, and SW. Occasional weak avalanches of material were visible near the crater. During 9-10 May wind entrained loose ash that was deposited along the Ceniza, Las Lajas, and Seca drainages. On 12 May a minor lahar descended the Ceniza drainage, carrying branches, tree trunks, and volcanic blocks up to 1.5 m in diameter. Minor incandescent over the crater was visible overnight during 12-13 and 15-16 May. Wind entrained ash deposits during 15-16 May causing localized “curtains” of ash.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Kita-Ioto | 10 May-16 May 2023 | New Activity / Unrest Cite this Report

Kita-Ioto
Volcano Islands (Japan)

Japan Coast Guard reported that a small area of bluish-white discolored water above Funka Asane, a submarine vent 4-5 km NW of Kita-Ioto, was visible on 11 May. This was the first time discolored water was seen over the vent in about two years.

Source: Japan Coast Guard

Aira | 10 May-16 May 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 8-15 May. Crater incandescence was observed nightly at Minamidake Crater. On 8 May sulfur dioxide emissions were extremely high at 3,900 tons per day. At 1315 on 9 May an explosion at Minamidake generated an ash plume that rose 1.2 km above the crater rim and drifted SW, and ejected blocks 1.1 km from the vent. Eruptive events at 1527, 1724, and 1817 on 11 May produced ash plumes that rose as high as 1.3 km and drifted NW and W. At Showa Crater eruptive events recorded at 1009, 1303, and 1401 on 8 May, at 0550, 0726, 2204, and 2321 on 11 May, at 1831 on 12 May, and at 0859 on 14 May produced ash plumes that rose as high as 1.7 km above the crater rim and drifted in multiple directions. Sulfur dioxide emissions were somewhat high on 12 May, averaging 1,800 tons per day. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from both craters.

Source: Japan Meteorological Agency (JMA)

Bezymianny | 10 May-16 May 2023 | Continuing ActivityCite this Report

Bezymianny
Central Kamchatka (Russia)

KVERT reported that activity at Bezymianny was generally characterized by gas-and-steam emissions, incandescence at the lava dome, and hot avalanches from the lava dome during 4-11 May. A daily thermal anomaly was identified daily in satellite images. The Aviation Color Code remained at Yellow (the second lowest 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)

Cotopaxi | 10 May-16 May 2023 | Continuing ActivityCite this Report

Cotopaxi
Ecuador

IG reported that moderate eruptive activity continued at Cotopaxi during 9-16 May. Daily seismic activity was characterized by long-period earthquakes and tremors indicating emissions; a few volcano-tectonic earthquakes were recorded during the week. Emissions of steam, gas, and variable amounts of ash were observed on most days. During 9-10 May plumes with moderate amounts of ash rose 2-3 km above the crater rim and drifted SW, N, and NE. Ashfall was reported in areas to the SW, including San Joaquín and San Agustín de Callo. On 11 May gas-and-steam plumes rose 700 m above the summit and drifted to the E and SE. Emissions with moderate ash content on 12 May rose 1-2 km above the crater rim and drifted to the SE; later that day ash plumes rose 700 m. On 13 May steam-and-gas emissions with low or no ash content rose 900 m above the summit and drifted S, and gas-and-ash plumes rose 800 m and drifted SE. On 15 May steam-and-ash plumes rose 400 m and drifted W and SW. Weather clouds often prevented views during 14-16 May. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).

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

Dukono | 10 May-16 May 2023 | Continuing ActivityCite this Report

Dukono
Halmahera

PVMBG reported that the eruption at Dukono was ongoing during 10-15 May. Daily dense white-and-gray ash plumes rose as high as 700 m above the summit and drifted E and N. The Alert Level remained at 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 | 10 May-16 May 2023 | Continuing ActivityCite this Report

Ebeko
Paramushir Island (Russia)

KVERT reported that moderate activity at Ebeko was ongoing during 4-11 May. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions during 4, 6-7, and 9-10 May generated ash plumes that rose as high as 4 km (13,100 ft) a.s.l. and drifted E. A thermal anomaly was identified in satellite images on 9 May. The Aviation Color Code remained at Orange (the second highest 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 | 10 May-16 May 2023 | Continuing ActivityCite this Report

Etna
Sicily (Italy)

INGV reported that an explosion at Etna’s SE Crater occurred at 0839 on 14 May and produced an ash emission that rapidly dispersed around the summit area. The Aviation Color Code was raised to Yellow at 0902 and then lowered back to Green at 1830 on 14 May. No significant variations in the seismic data were associated with the explosion.

Source: Sezione di Catania - Osservatorio Etneo (INGV)

Great Sitkin | 10 May-16 May 2023 | Continuing ActivityCite this Report

Great Sitkin
Andreanof Islands (USA)

AVO reported that lava likely continued to erupt at the summit of Great Sitkin during 9-16 May. Satellite data acquired on 11 May showed that the thick lava continued to expand towards the E but remained confined to the summit crater. Seismicity was low. Nothing significant was seen in satellite and webcam images during most of the week due to persistent weather clouds obscuring views. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Krakatau | 10 May-16 May 2023 | Continuing ActivityCite this Report

Krakatau
Sunda Strait

During 10-13 May PVMBG reported that white-and-gray and white-and-brown ash plumes generally rose as high as 200 m above Anak Krakatau’s summit and drifted SW and NW, though a few Volcano Observatory Notices for Aviation (VONAs) described higher plumes. At 1241 on 11 May a gray ash plume rose 1 km above summit and drifted SW. At 0920 on 12 May a dense gray ash plume rose 2.5 km and drifted SW. At 2320 a dense gray ash plume rose 1.5 km and drifted SW. An accompanying webcam image showed incandescent material being ejected above the vent. At 0710 on 13 May a dense gray ash plume rose 2 km and drifted SW. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay at least 5 km away from the crater.

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

Lewotolok | 10 May-16 May 2023 | Continuing ActivityCite this Report

Lewotolok
Lembata Island

PVMBG reported that the eruption at Lewotolok was ongoing during 9-16 May. Almost daily white-and-gray ash plumes generally rose as high as 500 m above the summit and drifted in variable directions. At 0632 on 11 May a white-to-gray ash plume rose 500 m and drifted SW. At 0645 and 0957 on 11 May white-to-gray ash plumes rose 400-600 m and drifted E and SE, respectively. Nighttime webcam images of incandescent material being ejected above the summit were posted in daily reports during 10-13 May. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the summit crater.

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

Merapi | 10 May-16 May 2023 | Continuing ActivityCite this Report

Merapi
Central Java

BPPTKG reported that the eruption at Merapi (on Java) continued during 5-11 May and seismicity remained at elevated levels. The SW lava dome produced 106 lava avalanches that traveled as far as 1.8 km down the SW flank (upstream in the Bebeng drainages). Morphological changes to the SW lava dome due to continuing collapses of material were evident in webcam images. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit based on location.

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

Nyamulagira | 10 May-16 May 2023 | Continuing ActivityCite this Report

Nyamulagira
DR Congo

The Observatoire Volcanologique de Goma (OVG) reported that the lava lake in Nyamulagira’s summit crater continued to be active during 30 April-6 May. A Sentinel satellite image from 7 May showed active lava flows traveling towards the NW part of the crater. Another image on 12 May showed active flows along the NE margin of the dark and cooler 7 May flows. Weather clouds and possible volcanic emissions obscured parts of the crater.

Sources: Observatoire Volcanologique de Goma (OVG), Sentinel Hub

Popocatepetl | 10 May-16 May 2023 | Continuing ActivityCite this Report

Popocatepetl
Mexico

CENAPRED reported that there were 127-281 daily steam, gas, and ash emissions and minor-to-moderate explosions recorded at Popocatépetl during 9-16 May. Plumes mostly drifted SE, ESE, and ENE. On 9 May minor explosions were recorded at 1141, 2009, and 2310, and on 10 May moderate explosions were recorded at 0152 and 0316. Ashfall was reported in Tlalmanalco (30 km NW) and Tetela del Volcán (20 km SW) in Morelos during 9-10 May. On 11 May minor explosions were recorded at 0135, 0215, and 1621, while moderate explosions were recorded at 0526, 0811, 0838, 1601, and 1646. Minor explosions occurred at 1318 and 1452 on 12 May. On 13 May minor explosions occurred at 0012, 0805, and 2146, and a moderate explosion occurred at 1012. Ashfall was reported in the municipalities of Nealtican (20 km E), Huejotzingo (21 km E), and Domingo Arenas (20 km NE). On 14 May minor explosions were recorded at 0605, 0711, 0831, 1413, 1439, and 2312; moderate explosions were recorded at 1253, 1444, 1608, and 1941. On 15 May the network detected minor explosions at 0033 and 0051, and moderate explosions at 0352, 0512, 0617, 0852, 1051, 1232, and 1613. Minor amounts of ash fell in the municipalities of Puebla (43 km E) and Atlixco (24 km SE) and moderate amounts fell in municipalities near the volcano to the S. Weather clouds prevented views on 16 May. According to the Washington VAAC daily ash plumes were identified in satellite images rising 6.1-7.3 km (20,000-24,000 ft) a.s.l. (0.7-1.9 km above the crater rim) and drifting E and SE. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale). CENAPRED urged people to respect the exclusion radius of 12 km and to not ascend the volcano.

Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC)

Reventador | 10 May-16 May 2023 | Continuing ActivityCite this Report

Reventador
Ecuador

IG reported that the eruption at Reventador was ongoing during 10-16 May. Seismicity was characterized by explosions, long-period earthquakes, harmonic tremors, and emission-related tremors. Steam, gas, and ash plumes were observed in some webcam images, though weather conditions occasionally obscured views. Ash emissions on 12 May rose 500 m above the crater rim and drifted N. On 14 May a steam-and-ash plume rose 250 m and drifted NE. On 16 May an ash plume rose as high as 1 km above the crater and drifted W and SW. Incandescence at the crater was visible at night during 10-12 and 16 May, and incandescent blocks rolled 200-700 m down the flanks. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Orange (the second highest level on a four-color scale).

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

Rincon de la Vieja | 10 May-16 May 2023 | Continuing ActivityCite this Report

Rincon de la Vieja
Costa Rica

OVSICORI-UNA reported that periodic phreatic eruptions occurred at Rincón de la Vieja during 9-16 May. Phreatic events recorded at 1945 on 9 May, at 1419 on 10 May, and at 1100 on 11 May produced plumes that rose less than 1.5 km above the crater rim. Additional phreatic activity were recorded at 2232 on 11 May, and at both 2332 and 2338 on 12 May, though it was not known if emissions were generated. A short-lived explosive event at 0258 on 14 May ejected material onto the N flank and caused lahars to descend the Penjamo, Azul, and Azufrado rivers. Phreatic events at 1155 and 1748 that same day produced emissions that rose 500 m and 1.5 km above the crater rim, respectively. Gas emissions were occasionally visible during 15-16 May.

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

Sangay | 10 May-16 May 2023 | Continuing ActivityCite this Report

Sangay
Ecuador

IG reported a high level of activity at Sangay during 9-16 May, though weather clouds prevented visual observations during most of the week. Ash plumes rose 500 m and drifted SW on 9 May. A webcam image from 1833 on 14 May showed lava flowing 500 m down the SE flank. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).

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

Santa Maria | 10 May-16 May 2023 | Continuing ActivityCite this Report

Santa Maria
Southwestern Guatemala

INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 10-16 May. Effusion from the Caliente dome complex fed lava flows that descended the San Isidro and Zanjón Seco drainages on the W and SW flanks; the main lava flow was 4.3 km long and remained active. Daily weak-to-moderate explosions generated gas, steam, and ash plumes that generally rose up to 800 m above the crater and drifted SE, S, SW, and W. Explosions were sometimes accompanied by block-and-ash flows that descended multiple flanks of the dome. Incandescence from the dome and lava flows was visible during the nights and early mornings. An average of 40 explosions per day were recorded during 9-10 and 13-14 May, generating ash plumes that rose up to 1 km above the dome and drifted S and SW. Ashfall was reported in Fincas El Patrocinio, El Faro (7 km S), Las Marías (10 km S), and others nearby on 10 May.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Semeru | 10 May-16 May 2023 | Continuing ActivityCite this Report

Semeru
Eastern Java

PVMBG reported that the eruption at Semeru continued during 10-16 May and a few Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued during the week. White-to-gray ash plumes that were sometimes dense rose 500-700 m above the summit and drifted S, SW, W, and N at 1115 on 10 May, at 0725 and 0830 on 12 May, at 0858, 1010, and 1241 on 13 May, at 0523 and 1656 on 14 May, and at 0757 on 16 May. 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, 100 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 | 10 May-16 May 2023 | Continuing ActivityCite this Report

Semisopochnoi
Aleutian Islands (USA)

AVO reported that low-level unrest continued at Semisopochnoi during 9-16 May. Weather clouds mostly obscured satellite and webcam views. Volcanic tremor was detected during 9-10 May; there was no evidence of explosive or earthquake activity in the geophysics data during the rest of the week. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Sheveluch | 10 May-16 May 2023 | Continuing ActivityCite this Report

Sheveluch
Central Kamchatka (Russia)

KVERT reported that the ongoing eruption at Sheveluch was generally characterized by occasional explosions, continuing lava-dome growth, incandescence, and strong fumarolic activity during 4-11 May. A thermal anomaly over the active crater and Karan lava dome area was identified in satellite images all week. Intense fumarolic activity was likely associated with dome growth. During 8-9 May ash from pyroclastic flow deposits on the SE flank were resuspended by winds and blown 60 km W based on satellite images. The Aviation Color Code remained at Orange (the second highest 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)

St. Helens | 10 May-16 May 2023 | Continuing ActivityCite this Report

St. Helens
Washington

USGS reported that at 2045 on 14 May a debris flow in Mount St. Helens' South Coldwater Creek destroyed a Highway SR 504 bridge, cutting off access and power to Johnston Ridge Observatory. While the loss of power interrupted a major telemetry hub, other stations remined operational and continued to provide data; the debris flow was recorded in seismic data from nearby stations. The source material in the flow originated from the climactic 1980 debris avalanche and eruption of Mount St. Helens. According to a news article at least 11 people had to spend the night at the Johnston Ridge Observatory and were airlifted out the next day. Officials noted that the highway will be closed for an indefinite amount of time.

Sources: US Geological Survey Cascades Volcano Observatory (CVO), KING-TV

Stromboli | 10 May-16 May 2023 | Continuing ActivityCite this Report

Stromboli
Aeolian Islands (Italy)

INGV reported ongoing Strombolian activity at Stromboli during 8-14 May. Activity was centered at two vents (one each at craters N1 and N2) in Area N, within the upper part of the Sciara del Fuoco, and from three vents in the Area C-S (South-Central Crater area) in the crater terrace area. Explosions at the N1 and N2 craters in Area N were low intensity and ejected coarse material (bombs and lapilli), sometimes mixed with ash at N1, as high as 80 m at a rate of 4-9 explosions per hour. Medium- to high-intensity explosions at the two vents in sector S2 (Area C-S) ejected ash sometimes mixed with coarse material at an average rate of 5-8 explosions per hour. Low-intensity gas explosions occurred at S1 in Area C-S. No significant activity was identified in Sector C in Area C-S.

Source: Sezione di Catania - Osservatorio Etneo (INGV)

Suwanosejima | 10 May-16 May 2023 | Continuing ActivityCite this Report

Suwanosejima
Ryukyu Islands (Japan)

JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 8-15 May and crater incandescence was reported nightly. Explosions recorded at 0701, 1200, and 2330 on 8 May produced ash plumes that rose as high as 1 km above the crater rim and mainly drifted SE. Explosions were also recorded at 1358 and 1648, though characteristics of associated emissions were unknown. Eruptive events at 2001 on 8 May, 1753 on 9 May, 0405, 0647, and 1236 on 11 May, and 1919 on 13 May generated ash plumes that rose as high as 1.3 km and generally drifted S, SW, and N. The Alert Level remained at 3 (on a 5-level scale) and residents were warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)

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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 Fuego
INSIVUMEH reported that a range of 1-7 weak explosions per hour were recorded at Fuego during 10-16 May. The explosions generated ash plumes that rose to a maximum height of 850 m above the crater and drifted up to 12 km E, SE, S, and SW. Occasional weak avalanches of material were visible near the crater. During 9-10 May wind entrained loose ash that was deposited along the Ceniza, Las Lajas, and Seca drainages. On 12 May a minor lahar descended the Ceniza drainage, carrying branches, tree trunks, and volcanic blocks up to 1.5 m in diameter. Minor incandescent over the crater was visible overnight during 12-13 and 15-16 May. Wind entrained ash deposits during 15-16 May causing localized “curtains” of ash.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Report for Kita-Ioto
Japan Coast Guard reported that a small area of bluish-white discolored water above Funka Asane, a submarine vent 4-5 km NW of Kita-Ioto, was visible on 11 May. This was the first time discolored water was seen over the vent in about two years.
Source: Japan Coast Guard

Report for Aira
JMA reported ongoing activity at both Minamidake Crater and Showa Crater (Aira Caldera’s Sakurajima volcano) during 8-15 May. Crater incandescence was observed nightly at Minamidake Crater. On 8 May sulfur dioxide emissions were extremely high at 3,900 tons per day. At 1315 on 9 May an explosion at Minamidake generated an ash plume that rose 1.2 km above the crater rim and drifted SW, and ejected blocks 1.1 km from the vent. Eruptive events at 1527, 1724, and 1817 on 11 May produced ash plumes that rose as high as 1.3 km and drifted NW and W. At Showa Crater eruptive events recorded at 1009, 1303, and 1401 on 8 May, at 0550, 0726, 2204, and 2321 on 11 May, at 1831 on 12 May, and at 0859 on 14 May produced ash plumes that rose as high as 1.7 km above the crater rim and drifted in multiple directions. Sulfur dioxide emissions were somewhat high on 12 May, averaging 1,800 tons per day. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from both craters.
Source: Japan Meteorological Agency (JMA)

Report for Bezymianny
KVERT reported that activity at Bezymianny was generally characterized by gas-and-steam emissions, incandescence at the lava dome, and hot avalanches from the lava dome during 4-11 May. A daily thermal anomaly was identified daily in satellite images. The Aviation Color Code remained at Yellow (the second lowest 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 Cotopaxi
IG reported that moderate eruptive activity continued at Cotopaxi during 9-16 May. Daily seismic activity was characterized by long-period earthquakes and tremors indicating emissions; a few volcano-tectonic earthquakes were recorded during the week. Emissions of steam, gas, and variable amounts of ash were observed on most days. During 9-10 May plumes with moderate amounts of ash rose 2-3 km above the crater rim and drifted SW, N, and NE. Ashfall was reported in areas to the SW, including San Joaquín and San Agustín de Callo. On 11 May gas-and-steam plumes rose 700 m above the summit and drifted to the E and SE. Emissions with moderate ash content on 12 May rose 1-2 km above the crater rim and drifted to the SE; later that day ash plumes rose 700 m. On 13 May steam-and-gas emissions with low or no ash content rose 900 m above the summit and drifted S, and gas-and-ash plumes rose 800 m and drifted SE. On 15 May steam-and-ash plumes rose 400 m and drifted W and SW. Weather clouds often prevented views during 14-16 May. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)

Report for Dukono
PVMBG reported that the eruption at Dukono was ongoing during 10-15 May. Daily dense white-and-gray ash plumes rose as high as 700 m above the summit and drifted E and N. The Alert Level remained at 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 activity at Ebeko was ongoing during 4-11 May. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions during 4, 6-7, and 9-10 May generated ash plumes that rose as high as 4 km (13,100 ft) a.s.l. and drifted E. A thermal anomaly was identified in satellite images on 9 May. The Aviation Color Code remained at Orange (the second highest 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 explosion at Etna’s SE Crater occurred at 0839 on 14 May and produced an ash emission that rapidly dispersed around the summit area. The Aviation Color Code was raised to Yellow at 0902 and then lowered back to Green at 1830 on 14 May. No significant variations in the seismic data were associated with the explosion.
Source: Sezione di Catania - Osservatorio Etneo (INGV)

Report for Great Sitkin
AVO reported that lava likely continued to erupt at the summit of Great Sitkin during 9-16 May. Satellite data acquired on 11 May showed that the thick lava continued to expand towards the E but remained confined to the summit crater. Seismicity was low. Nothing significant was seen in satellite and webcam images during most of the week due to persistent weather clouds obscuring views. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Krakatau
During 10-13 May PVMBG reported that white-and-gray and white-and-brown ash plumes generally rose as high as 200 m above Anak Krakatau’s summit and drifted SW and NW, though a few Volcano Observatory Notices for Aviation (VONAs) described higher plumes. At 1241 on 11 May a gray ash plume rose 1 km above summit and drifted SW. At 0920 on 12 May a dense gray ash plume rose 2.5 km and drifted SW. At 2320 a dense gray ash plume rose 1.5 km and drifted SW. An accompanying webcam image showed incandescent material being ejected above the vent. At 0710 on 13 May a dense gray ash plume rose 2 km and drifted SW. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay at least 5 km away from the crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Lewotolok
PVMBG reported that the eruption at Lewotolok was ongoing during 9-16 May. Almost daily white-and-gray ash plumes generally rose as high as 500 m above the summit and drifted in variable directions. At 0632 on 11 May a white-to-gray ash plume rose 500 m and drifted SW. At 0645 and 0957 on 11 May white-to-gray ash plumes rose 400-600 m and drifted E and SE, respectively. Nighttime webcam images of incandescent material being ejected above the summit were posted in daily reports during 10-13 May. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the summit crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Merapi
BPPTKG reported that the eruption at Merapi (on Java) continued during 5-11 May and seismicity remained at elevated levels. The SW lava dome produced 106 lava avalanches that traveled as far as 1.8 km down the SW flank (upstream in the Bebeng drainages). Morphological changes to the SW lava dome due to continuing collapses of material were evident in webcam images. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit based on location.
Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)

Report for Nyamulagira
The Observatoire Volcanologique de Goma (OVG) reported that the lava lake in Nyamulagira’s summit crater continued to be active during 30 April-6 May. A Sentinel satellite image from 7 May showed active lava flows traveling towards the NW part of the crater. Another image on 12 May showed active flows along the NE margin of the dark and cooler 7 May flows. Weather clouds and possible volcanic emissions obscured parts of the crater.
Sources: Observatoire Volcanologique de Goma (OVG), Sentinel Hub

Report for Popocatepetl
CENAPRED reported that there were 127-281 daily steam, gas, and ash emissions and minor-to-moderate explosions recorded at Popocatépetl during 9-16 May. Plumes mostly drifted SE, ESE, and ENE. On 9 May minor explosions were recorded at 1141, 2009, and 2310, and on 10 May moderate explosions were recorded at 0152 and 0316. Ashfall was reported in Tlalmanalco (30 km NW) and Tetela del Volcán (20 km SW) in Morelos during 9-10 May. On 11 May minor explosions were recorded at 0135, 0215, and 1621, while moderate explosions were recorded at 0526, 0811, 0838, 1601, and 1646. Minor explosions occurred at 1318 and 1452 on 12 May. On 13 May minor explosions occurred at 0012, 0805, and 2146, and a moderate explosion occurred at 1012. Ashfall was reported in the municipalities of Nealtican (20 km E), Huejotzingo (21 km E), and Domingo Arenas (20 km NE). On 14 May minor explosions were recorded at 0605, 0711, 0831, 1413, 1439, and 2312; moderate explosions were recorded at 1253, 1444, 1608, and 1941. On 15 May the network detected minor explosions at 0033 and 0051, and moderate explosions at 0352, 0512, 0617, 0852, 1051, 1232, and 1613. Minor amounts of ash fell in the municipalities of Puebla (43 km E) and Atlixco (24 km SE) and moderate amounts fell in municipalities near the volcano to the S. Weather clouds prevented views on 16 May. According to the Washington VAAC daily ash plumes were identified in satellite images rising 6.1-7.3 km (20,000-24,000 ft) a.s.l. (0.7-1.9 km above the crater rim) and drifting E and SE. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale). CENAPRED urged people to respect the exclusion radius of 12 km and to not ascend the volcano.
Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC)

Report for Reventador
IG reported that the eruption at Reventador was ongoing during 10-16 May. Seismicity was characterized by explosions, long-period earthquakes, harmonic tremors, and emission-related tremors. Steam, gas, and ash plumes were observed in some webcam images, though weather conditions occasionally obscured views. Ash emissions on 12 May rose 500 m above the crater rim and drifted N. On 14 May a steam-and-ash plume rose 250 m and drifted NE. On 16 May an ash plume rose as high as 1 km above the crater and drifted W and SW. Incandescence at the crater was visible at night during 10-12 and 16 May, and incandescent blocks rolled 200-700 m down the flanks. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Orange (the second highest level on a four-color scale).
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)

Report for Rincon de la Vieja
OVSICORI-UNA reported that periodic phreatic eruptions occurred at Rincón de la Vieja during 9-16 May. Phreatic events recorded at 1945 on 9 May, at 1419 on 10 May, and at 1100 on 11 May produced plumes that rose less than 1.5 km above the crater rim. Additional phreatic activity were recorded at 2232 on 11 May, and at both 2332 and 2338 on 12 May, though it was not known if emissions were generated. A short-lived explosive event at 0258 on 14 May ejected material onto the N flank and caused lahars to descend the Penjamo, Azul, and Azufrado rivers. Phreatic events at 1155 and 1748 that same day produced emissions that rose 500 m and 1.5 km above the crater rim, respectively. Gas emissions were occasionally visible during 15-16 May.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Report for Sangay
IG reported a high level of activity at Sangay during 9-16 May, though weather clouds prevented visual observations during most of the week. Ash plumes rose 500 m and drifted SW on 9 May. A webcam image from 1833 on 14 May showed lava flowing 500 m down the SE flank. Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Servicio Nacional de Gestión de Riesgos y Emergencias (SNGRE)

Report for Santa Maria
INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 10-16 May. Effusion from the Caliente dome complex fed lava flows that descended the San Isidro and Zanjón Seco drainages on the W and SW flanks; the main lava flow was 4.3 km long and remained active. Daily weak-to-moderate explosions generated gas, steam, and ash plumes that generally rose up to 800 m above the crater and drifted SE, S, SW, and W. Explosions were sometimes accompanied by block-and-ash flows that descended multiple flanks of the dome. Incandescence from the dome and lava flows was visible during the nights and early mornings. An average of 40 explosions per day were recorded during 9-10 and 13-14 May, generating ash plumes that rose up to 1 km above the dome and drifted S and SW. Ashfall was reported in Fincas El Patrocinio, El Faro (7 km S), Las Marías (10 km S), and others nearby on 10 May.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Report for Semeru
PVMBG reported that the eruption at Semeru continued during 10-16 May and a few Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued during the week. White-to-gray ash plumes that were sometimes dense rose 500-700 m above the summit and drifted S, SW, W, and N at 1115 on 10 May, at 0725 and 0830 on 12 May, at 0858, 1010, and 1241 on 13 May, at 0523 and 1656 on 14 May, and at 0757 on 16 May. 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, 100 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 low-level unrest continued at Semisopochnoi during 9-16 May. Weather clouds mostly obscured satellite and webcam views. Volcanic tremor was detected during 9-10 May; there was no evidence of explosive or earthquake activity in the geophysics data during the rest of the week. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Sheveluch
KVERT reported that the ongoing eruption at Sheveluch was generally characterized by occasional explosions, continuing lava-dome growth, incandescence, and strong fumarolic activity during 4-11 May. A thermal anomaly over the active crater and Karan lava dome area was identified in satellite images all week. Intense fumarolic activity was likely associated with dome growth. During 8-9 May ash from pyroclastic flow deposits on the SE flank were resuspended by winds and blown 60 km W based on satellite images. The Aviation Color Code remained at Orange (the second highest 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 St. Helens
USGS reported that at 2045 on 14 May a debris flow in Mount St. Helens' South Coldwater Creek destroyed a Highway SR 504 bridge, cutting off access and power to Johnston Ridge Observatory. While the loss of power interrupted a major telemetry hub, other stations remined operational and continued to provide data; the debris flow was recorded in seismic data from nearby stations. The source material in the flow originated from the climactic 1980 debris avalanche and eruption of Mount St. Helens. According to a news article at least 11 people had to spend the night at the Johnston Ridge Observatory and were airlifted out the next day. Officials noted that the highway will be closed for an indefinite amount of time.
Sources: US Geological Survey Cascades Volcano Observatory (CVO), KING-TV

Report for Stromboli
INGV reported ongoing Strombolian activity at Stromboli during 8-14 May. Activity was centered at two vents (one each at craters N1 and N2) in Area N, within the upper part of the Sciara del Fuoco, and from three vents in the Area C-S (South-Central Crater area) in the crater terrace area. Explosions at the N1 and N2 craters in Area N were low intensity and ejected coarse material (bombs and lapilli), sometimes mixed with ash at N1, as high as 80 m at a rate of 4-9 explosions per hour. Medium- to high-intensity explosions at the two vents in sector S2 (Area C-S) ejected ash sometimes mixed with coarse material at an average rate of 5-8 explosions per hour. Low-intensity gas explosions occurred at S1 in Area C-S. No significant activity was identified in Sector C in Area C-S.
Source: Sezione di Catania - Osservatorio Etneo (INGV)

Report for Suwanosejima
JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 8-15 May and crater incandescence was reported nightly. Explosions recorded at 0701, 1200, and 2330 on 8 May produced ash plumes that rose as high as 1 km above the crater rim and mainly drifted SE. Explosions were also recorded at 1358 and 1648, though characteristics of associated emissions were unknown. Eruptive events at 2001 on 8 May, 1753 on 9 May, 0405, 0647, and 1236 on 11 May, and 1919 on 13 May generated ash plumes that rose as high as 1.3 km and generally drifted S, SW, and N. The Alert Level remained at 3 (on a 5-level scale) and residents were warned to stay 2 km away from the crater.
Source: Japan Meteorological Agency (JMA)