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 12 April-18 April 2023
Name	Location	Eruption Start Date	Report Status
Bezymianny	Central Kamchatka (Russia)	2016 Dec 5	New
Nevado del Ruiz	Colombia	2014 Nov 18	New
Sheveluch	Central Kamchatka (Russia)	1999 Aug 15	New
Aira	Kyushu (Japan)	2017 Mar 25	Continuing
Aniakchak	Alaska Peninsula, Alaska	—	Continuing
Asamayama	Honshu (Japan)	—	Continuing
Cotopaxi	Ecuador	—	Continuing
Dukono	Halmahera	1933 Aug 13	Continuing
Ebeko	Paramushir Island (Russia)	2022 Jun 11	Continuing
Fuego	South-Central Guatemala	2002 Jan 4	Continuing
Great Sitkin	Andreanof Islands (USA)	2021 May 25	Continuing
Ibu	Halmahera	2008 Apr 5	Continuing
Karangetang	Sangihe Islands	2018 Nov 25	Continuing
Lewotolok	Lembata Island	2020 Nov 27	Continuing
Merapi	Central Java	2020 Dec 31	Continuing
Rincon de la Vieja	Costa Rica	2021 Jun 28	Continuing
Sabancaya	Peru	2016 Nov 6	Continuing
Santa Maria	Southwestern Guatemala	1922 Jun 22	Continuing
Semeru	Eastern Java	2017 Jun 6	Continuing
Semisopochnoi	Aleutian Islands (USA)	—	Continuing
Suwanosejima	Ryukyu Islands (Japan)	2004 Oct 23	Continuing

All times are local unless otherwise stated.

Bezymianny | 12 April-18 April 2023 | New Activity / Unrest Cite this Report

Bezymianny
Central Kamchatka (Russia)

KVERT reported that the eruption at Bezymianny intensified to a significant explosive phase starting from 1738 on 7 April and ending before 0906 on 8 April (local times). Based on webcam and satellite data ash plumes rose 10-12 km (32,800-39,400 ft) a.s.l. and drifted 2,800 km E. Notable amounts of ash fell at the Apakhonchich station. A daily thermal anomaly from continuing lava effusion was identified in satellite images during 8-14 April. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Nevado del Ruiz | 12 April-18 April 2023 | New Activity / Unrest Cite this Report

Nevado del Ruiz
Colombia

Servicio Geológico Colombiano’s (SGC) reported that the eruption at Nevado del Ruiz continued during 11-18 April and was characterized by gas, steam, and ash emissions, thermal anomalies at the lava dome in Arenas Crater, and elevated seismicity. Seismic signals indicating rock-fracturing events continued to be located 2-6 km SW of Arenas Crater at depths of 2-4 km, though on 12 and 16 April signals were also located in the NE sector of the volcano at depths of 0.5-5 km. The number of daily events fluctuated through the week. Additionally, signals indicating fluid movement fluctuated in intensity and were associated with daily ash emissions. On 11 April ash-and-gas plumes rose as high as 2.5 km above the crater rim and drifted SW and NW, causing ashfall in the municipalities of Villamaría (Caldas) and Filandia (Quindío). Ash-and-gas plumes that rose as high as 1.8 km drifted SW and NW on 12 April, and 1.5 km high plumes drifted SW on 13 April. During 0759-1113 on 14 April and from 1515 on 14 April to 1257 on 15 April seismicity activity intensified and corresponded to continuous ash emissions that rose as high as 1.5 km and drifted SW. These emissions were visible from the municipalities of Murillo and Manizales. Later that day gas-and-ash plumes rose to 1.6 km and drifted NW. According to a news article 87 people had self-evacuated after the government called for the voluntary evacuation of around 2,500 families on 5 April. The Alert Level was remained at Orange, Level II (the second highest level on a four-level scale).

Sources: Servicio Geológico Colombiano (SGC), CNN

Sheveluch | 12 April-18 April 2023 | New Activity / Unrest Cite this Report

Sheveluch
Central Kamchatka (Russia)

According to KVERT a significant eruption at Sheveluch began at 0110 on 11 April, local time. During the most intense phase of activity ash plumes possibly rose as high as 15.8 km (52,000 ft) a.s.l., a significant sulfur dioxide signature was detected in the plume, pyroclastic flows traveled notable distances, and ash-and-lapilli-fall impacted residents. Strong explosions continued during the morning of 12 April. At 0730 on 12 April satellite images showed ash plumes rising to 8 km (26,200 ft) a.s.l., though parts of the large ash plume generated earlier extended 600 km SW and 1,050 km ESE. The explosions weakened by 1710 when ash plumes were only rising to 4.5 km (14,800 ft) a.s.l. and drifting ESE; at 1801 KVERT issued a Volcano Observatory Notice for Aviation (VONA) lowering the Aviation Color Code to Orange. By 2310 ash extended as far as 3,000 km E. KVERT noted that ash deposits in Klyuchi were as deep as 8.5 cm, and ashfall was reported in Kozyrevsk, Maiskoye, Atlasovo, Lazo, and Esso during 10-12 April. According to news sources, the ash-and-gas plumes drifted E toward the Aleutian Islands and reached the Gulf of Alaska by 13 April, causing flight disruptions. More than 100 flights involving Alaska airspace were cancelled due to the plume. Flight cancellations were also reported in NW Canada (British Columbia) during 13-14 April. Alaskan flight schedules were mostly back to normal by 15 April, with only minor delays and far fewer cancellations; a few cancellations continued to be reported in Canada.

On 13 April Kamchatka Volcanological Station (KVS) volcanologists inspected pyroclastic flow deposits that had stopped about 600 m from the Klyuchi-Ust-Kamchatsk federal highway. They walked about 1 km through deep snow (1 m) covered in 6 cm of ash and noted that some parts of the deposits were hot. Steam rose from downed smoldering trees. One picture showed a large block lodged high up in a bare tree. They also noted that the pyroclastic flow deposits were thin with very few large fragments, different from previous flows from Sheveluch. Clearing weather on 15 April revealed that most of the previous lava-dome complex was gone and there was a new crater 1 km in diameter from which voluminous steam-and-gas plumes were rising. Evidence suggested that there had been a directed blast to the SE, and pyroclastic flows traveled more than 20 km.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Kamchatka Volcanological Station, Institute of Volcanology and Seismology (IVS) of the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS), Anchorage Daily News, Canadian Broadcasting Corporation (CBC), Cabin Radio

Aira | 12 April-18 April 2023 | Continuing ActivityCite this Report

Aira
Kyushu (Japan)

JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 10-17 April, with crater incandescence visible nightly. Very small eruptive events occasionally occurred during 10-14 April. Two eruptive events on 17 April produced ash plumes that rose as high as 1.5 km and drifted S. 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)

Aniakchak | 12 April-18 April 2023 | Continuing ActivityCite this Report

Aniakchak
Alaska Peninsula, Alaska

On 13 April AVO issued an Information Statement about the ongoing unrest at Aniakchak. Measurements of the earthquake rate in the ongoing swarm were disrupted by a partial network outage that began on 4 March and reduced the ability to detect smaller earthquakes. Earthquake activity continued to be above background levels with a M 3.3 on 6 April as the largest recent event. In addition to the earthquake swarm, high rates of deformation were detected in radar data. A zone of uplift centered within the W side of the caldera was first detected between 4 and 27 February. The ground uplift rates were about 4 cm per week during February-March and about 3 cm per week during 23 March-4 April. These uplift rates are at the high end of those observed for restless volcanoes worldwide.

Seismic and deformation data suggested that magma was intruding beneath the caldera at a depth of 3-4 km below sea level. AVO noted that unrest at calderas such as Aniakchak sometimes lasts for many months or even years and could be variable . If an eruption were to occur, it could be after a period of months or years and would likely be preceded by additional signals that would allow AVO to provide advance warning. Aniakchak has a local monitoring network consisting of six seismometers, a web camera, and an infrasound sensor, as well as with satellite remote sensing data and regional infrasound and lightning networks. AVO recently installed an additional seismic station and web camera in Port Heiden, 26 km NW. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Asamayama | 12 April-18 April 2023 | Continuing ActivityCite this Report

Asamayama
Honshu (Japan)

JMA reported that minor inflation on Asamayama's W flank persisted during 10-17 April. The daily number of shallow volcanic earthquakes was 40-80 during 10-14 April and around 40 during 14-17 April. Sulfur dioxide emissions were high at 700 tons per day on 14 April. The Alert Level remained at a 2 (on a scale of 1-5) and warned the public that ejected blocks and pyroclastic flows may travel as far as 2 km from the crater during an eruption.

Source: Japan Meteorological Agency (JMA)

Cotopaxi | 12 April-18 April 2023 | Continuing ActivityCite this Report

Cotopaxi
Ecuador

IG reported that eruptive activity at Cotopaxi was ongoing during 11-18 April, though cloudy weather often prevented webcam and satellite views. A small secondary lahar descended the Agualongo drainage on the SW flank on 11 April. Ash-and-gas plumes on 12 April rose as high as 1.5 km above the crater rim and drifted W and SW. Muddy water in a drainage on the NW flank was visible on 15 April. Daily gas-and-steam emissions were visible during 13-18 April, rising as high as 300 m and drifted W. 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 | 12 April-18 April 2023 | Continuing ActivityCite this Report

Dukono
Halmahera

PVMBG reported that the eruption at Dukono was ongoing during 12-17 April. Daily dense white-and-gray ash plumes rose as high as 400 m above the summit and drifted E. No ash plumes were reported by PVMBG on 12 April, but according to the Darwin VAAC an ash plume rose to 2.1 km (7,000 ft) a.s.l., or about 900 m above the summit, and drifted E. 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.

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

Ebeko | 12 April-18 April 2023 | Continuing ActivityCite this Report

Ebeko
Paramushir Island (Russia)

According to the Tokyo VAAC a possible ash plume at Ebeko was visible in a satellite image at 0920 on 14 April rising to 2.4 (8,000 ft) a.s.l. and drifted NE. The plume had dissipated by 1120. Another plume from a possible eruption was identified in satellite images at 1300, rising to 3.7 (12,000 ft) a.s.l. and drifting N. The plume was no longer visible or had dissipated by 1720. At 1452 on 16 April an ash plume rose to 3 km (10,000 ft) a.s.l. and drifted NE.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)

Fuego | 12 April-18 April 2023 | Continuing ActivityCite this Report

Fuego
South-Central Guatemala

INSIVUMEH reported that 4-13 explosions per hour were generally recorded at Fuego during 11-18 April, generating daily ash plumes that rose as high as 1.7 km above the crater rim and drifted as far as 30 km SW, S, SE, and E. Daily ashfall was recorded in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), La Rochela, San Andrés Osuna, Ceylon, Finca La Asunción, El Zapote (10 km S), Alotenángo (8 km ENE), and other areas to the N and NE. Daily block avalanches descended multiple drainages including the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Honda, Las Lajas (SE), and El Jute (ESE), and often reached vegetated areas. Daily shock waves rattled structures in communities around the volcano and rumbling was often heard. Explosions ejected incandescent material as high as 350 m above the summit on most days.

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

Great Sitkin | 12 April-18 April 2023 | Continuing ActivityCite this Report

Great Sitkin
Andreanof Islands (USA)

AVO reported that lava continued to slowly erupt at the summit of Great Sitkin during 11-17 April, producing a thick lava flow that expanded mostly to the E. Seismicity was low, and during 11-13 April only a few small events were detected. Elevated surface temperatures were identified in satellite images during 16-17 April, and steam emissions were visible in webcam views during 17-18 April. Weather clouds often obscured satellite and webcam views during most 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 color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Ibu | 12 April-18 April 2023 | Continuing ActivityCite this Report

Ibu
Halmahera

PVMBG reported that the eruption at Ibu continued during 12-18 April. White-and-gray plumes of variable densities rose as high as 800 m above the summit and drifted NE, S, SW, and NW. The Alert Level remained at a 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side.

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

Karangetang | 12 April-18 April 2023 | Continuing ActivityCite this Report

Karangetang
Sangihe Islands

Webcam images of Karangetang captured in the PVMBG daily reports periodically showed small areas of incandescence at the summit craters during 11-17 April. 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.

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

Lewotolok | 12 April-18 April 2023 | Continuing ActivityCite this Report

Lewotolok
Lembata Island

PVMBG reported that the eruption at Lewotolok was ongoing during 12-17 April. White steam-and-gas plumes of variable densities were seen on most days rising as high as 700 m above the summit and drifting NE, E, and SE. On 13, 15, and 17 April white-and-gray plumes rose as high as 500 m and drifted NW, NE, E, and SE. 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 | 12 April-18 April 2023 | Continuing ActivityCite this Report

Merapi
Central Java

BPPTKG reported that the eruption at Merapi (on Java) continued during 7-13 April and seismicity remained at high levels. The SW lava dome produced 132 lava avalanches that traveled as far as 2 km down the SW flank (upstream in the Bebeng and Boyong drainages). Morphological changes to the SW lava dome were evident in webcam images 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)

Rincon de la Vieja | 12 April-18 April 2023 | Continuing ActivityCite this Report

Rincon de la Vieja
Costa Rica

OVSICORI-UNA reported that small phreatic eruptions, often in association with observed emissions, occurred at Rincón de la Vieja during 11-17 April. A small phreatic eruption on 11 April consisted of several pulses of activity recorded during 0653-0700 and at 0743. Gas-and-steam plumes rose 500 m above the crater rim. A small phreatic event was recorded late in the evening. An event at 0450 on 12 April produced a gas-and-steam plume that rose 500 m and another was recorded at 1920 with no visual observations reported. Gas-and-steam emissions from a phreatic event were seen at 0632 on 13 April; an event was recorded at 1826 with no visual observations reported. At 0936 on 14 April an event produced a gas-and-steam plume that rose as high as 2 km and was seen from Curubandé. The event was preceded by a swarm of long-period earthquakes five hours prior to the eruption; sediments were possibly ejected from the crater lake and deposited on the crater floor. A small phreatic eruption at 0647 on 16 April ejected material out of the crater and produced a gas-and-steam plume that rose 2 km. A smaller emission rose 500 m at 0957 and at 2235 an event generated a plume that rose 500 m. At 1237 on 17 April a phreatic event produced a plume that rose 1.5 km above the crater rim and a brief event was recorded at 0722 on 18 April.

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

Sabancaya | 12 April-18 April 2023 | Continuing ActivityCite this Report

Sabancaya
Peru

Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 10-16 April with a daily average of 41 explosions. Gas-and-ash plumes rose as high as 2.5 km above the summit and drifted NW, W, SW, and S. Six thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. 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)

Santa Maria | 12 April-18 April 2023 | Continuing ActivityCite this Report

Santa Maria
Southwestern Guatemala

INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 12-18 April. 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. Incandescence from the dome and the lava flows was frequently visible at night. Avalanches down the N, E, S, and SW flanks of the dome were sometimes generated from the lava-flow front and margins. Daily weak or weak-to-moderate explosions were recorded by the seismic network and on most days the explosions generated ash plumes that rose as high as 1 km above the complex and drifted mainly E, S, and SW. Weak rumbling was barely heard on nearby farms during 16-17 April. Residents were reminded to stay at least 6 km away from the complex.

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

Semeru | 12 April-18 April 2023 | Continuing ActivityCite this Report

Semeru
Eastern Java

PVMBG reported that the eruption at Semeru continued during 12-18 April and daily Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued through the week. At 0747 on 12 April a dense white-to-gray plume rose 600 m above the summit and drifted N. On 13 April at 1135 a gray-to-brown ash plume rose 400 m and drifted NE, at 1249 a dense gray ash plume rose 500 m and drifted N and NE, and at 1709 a dense white-to-gray ash plume rose 600 m and drifted E. At 0529 on 14 April a white-to-brown ash plume rose 500 m and drifted S. White-to-gray ash plumes at 0606 and 0731 on 15 April rose 600-700 m and drifted N and NE. At 0551 on 16 April a dense white-to-gray ash plume rose 1 km and drifted N. On 17 April at 0614 a medium-density white-to-brown ash plume rose 700 m and drifted S and at 0847 a white-to-gray ash plume rose 600 m and also drifted S. At 0540 and 0708 on 18 April dense white-to-gray ash plumes rose 500-600 m and drifted S and W. The Alert Level remained at 3 (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 originating on Semeru, 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 | 12 April-18 April 2023 | Continuing ActivityCite this Report

Semisopochnoi
Aleutian Islands (USA)

AVO reported that low-level unrest continued at Semisopochnoi during 12-18 April. No eruptive activity was observed, though some weak seismicity was recorded. Cloudy weather often prevented webcam and satellite views during most 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 color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Suwanosejima | 12 April-18 April 2023 | Continuing ActivityCite this Report

Suwanosejima
Ryukyu Islands (Japan)

JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 10-17 April. Eruptive activity produced ash plumes during 12-14 and 17 April that rose as high as 1.5 km above the crater rim and drifted NW, S, SE, and E. Large blocks were ejected as far as 500 m from the vent. Crater incandescence was visible nightly. 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 Bezymianny
KVERT reported that the eruption at Bezymianny intensified to a significant explosive phase starting from 1738 on 7 April and ending before 0906 on 8 April (local times). Based on webcam and satellite data ash plumes rose 10-12 km (32,800-39,400 ft) a.s.l. and drifted 2,800 km E. Notable amounts of ash fell at the Apakhonchich station. A daily thermal anomaly from continuing lava effusion was identified in satellite images during 8-14 April. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Report for Nevado del Ruiz
Servicio Geológico Colombiano’s (SGC) reported that the eruption at Nevado del Ruiz continued during 11-18 April and was characterized by gas, steam, and ash emissions, thermal anomalies at the lava dome in Arenas Crater, and elevated seismicity. Seismic signals indicating rock-fracturing events continued to be located 2-6 km SW of Arenas Crater at depths of 2-4 km, though on 12 and 16 April signals were also located in the NE sector of the volcano at depths of 0.5-5 km. The number of daily events fluctuated through the week. Additionally, signals indicating fluid movement fluctuated in intensity and were associated with daily ash emissions. On 11 April ash-and-gas plumes rose as high as 2.5 km above the crater rim and drifted SW and NW, causing ashfall in the municipalities of Villamaría (Caldas) and Filandia (Quindío). Ash-and-gas plumes that rose as high as 1.8 km drifted SW and NW on 12 April, and 1.5 km high plumes drifted SW on 13 April. During 0759-1113 on 14 April and from 1515 on 14 April to 1257 on 15 April seismicity activity intensified and corresponded to continuous ash emissions that rose as high as 1.5 km and drifted SW. These emissions were visible from the municipalities of Murillo and Manizales. Later that day gas-and-ash plumes rose to 1.6 km and drifted NW. According to a news article 87 people had self-evacuated after the government called for the voluntary evacuation of around 2,500 families on 5 April. The Alert Level was remained at Orange, Level II (the second highest level on a four-level scale).
Sources: Servicio Geológico Colombiano (SGC), CNN

Report for Sheveluch
According to KVERT a significant eruption at Sheveluch began at 0110 on 11 April, local time. During the most intense phase of activity ash plumes possibly rose as high as 15.8 km (52,000 ft) a.s.l., a significant sulfur dioxide signature was detected in the plume, pyroclastic flows traveled notable distances, and ash-and-lapilli-fall impacted residents. Strong explosions continued during the morning of 12 April. At 0730 on 12 April satellite images showed ash plumes rising to 8 km (26,200 ft) a.s.l., though parts of the large ash plume generated earlier extended 600 km SW and 1,050 km ESE. The explosions weakened by 1710 when ash plumes were only rising to 4.5 km (14,800 ft) a.s.l. and drifting ESE; at 1801 KVERT issued a Volcano Observatory Notice for Aviation (VONA) lowering the Aviation Color Code to Orange. By 2310 ash extended as far as 3,000 km E. KVERT noted that ash deposits in Klyuchi were as deep as 8.5 cm, and ashfall was reported in Kozyrevsk, Maiskoye, Atlasovo, Lazo, and Esso during 10-12 April. According to news sources, the ash-and-gas plumes drifted E toward the Aleutian Islands and reached the Gulf of Alaska by 13 April, causing flight disruptions. More than 100 flights involving Alaska airspace were cancelled due to the plume. Flight cancellations were also reported in NW Canada (British Columbia) during 13-14 April. Alaskan flight schedules were mostly back to normal by 15 April, with only minor delays and far fewer cancellations; a few cancellations continued to be reported in Canada.

On 13 April Kamchatka Volcanological Station (KVS) volcanologists inspected pyroclastic flow deposits that had stopped about 600 m from the Klyuchi-Ust-Kamchatsk federal highway. They walked about 1 km through deep snow (1 m) covered in 6 cm of ash and noted that some parts of the deposits were hot. Steam rose from downed smoldering trees. One picture showed a large block lodged high up in a bare tree. They also noted that the pyroclastic flow deposits were thin with very few large fragments, different from previous flows from Sheveluch. Clearing weather on 15 April revealed that most of the previous lava-dome complex was gone and there was a new crater 1 km in diameter from which voluminous steam-and-gas plumes were rising. Evidence suggested that there had been a directed blast to the SE, and pyroclastic flows traveled more than 20 km.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Kamchatka Volcanological Station, Institute of Volcanology and Seismology (IVS) of the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS), Anchorage Daily News, Canadian Broadcasting Corporation (CBC), Cabin Radio

Report for Aira
JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 10-17 April, with crater incandescence visible nightly. Very small eruptive events occasionally occurred during 10-14 April. Two eruptive events on 17 April produced ash plumes that rose as high as 1.5 km and drifted S. 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 Aniakchak
On 13 April AVO issued an Information Statement about the ongoing unrest at Aniakchak. Measurements of the earthquake rate in the ongoing swarm were disrupted by a partial network outage that began on 4 March and reduced the ability to detect smaller earthquakes. Earthquake activity continued to be above background levels with a M 3.3 on 6 April as the largest recent event. In addition to the earthquake swarm, high rates of deformation were detected in radar data. A zone of uplift centered within the W side of the caldera was first detected between 4 and 27 February. The ground uplift rates were about 4 cm per week during February-March and about 3 cm per week during 23 March-4 April. These uplift rates are at the high end of those observed for restless volcanoes worldwide.

Seismic and deformation data suggested that magma was intruding beneath the caldera at a depth of 3-4 km below sea level. AVO noted that unrest at calderas such as Aniakchak sometimes lasts for many months or even years and could be variable . If an eruption were to occur, it could be after a period of months or years and would likely be preceded by additional signals that would allow AVO to provide advance warning. Aniakchak has a local monitoring network consisting of six seismometers, a web camera, and an infrasound sensor, as well as with satellite remote sensing data and regional infrasound and lightning networks. AVO recently installed an additional seismic station and web camera in Port Heiden, 26 km NW. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Asamayama
JMA reported that minor inflation on Asamayama's W flank persisted during 10-17 April. The daily number of shallow volcanic earthquakes was 40-80 during 10-14 April and around 40 during 14-17 April. Sulfur dioxide emissions were high at 700 tons per day on 14 April. The Alert Level remained at a 2 (on a scale of 1-5) and warned the public that ejected blocks and pyroclastic flows may travel as far as 2 km from the crater during an eruption.
Source: Japan Meteorological Agency (JMA)

Report for Cotopaxi
IG reported that eruptive activity at Cotopaxi was ongoing during 11-18 April, though cloudy weather often prevented webcam and satellite views. A small secondary lahar descended the Agualongo drainage on the SW flank on 11 April. Ash-and-gas plumes on 12 April rose as high as 1.5 km above the crater rim and drifted W and SW. Muddy water in a drainage on the NW flank was visible on 15 April. Daily gas-and-steam emissions were visible during 13-18 April, rising as high as 300 m and drifted W. 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 12-17 April. Daily dense white-and-gray ash plumes rose as high as 400 m above the summit and drifted E. No ash plumes were reported by PVMBG on 12 April, but according to the Darwin VAAC an ash plume rose to 2.1 km (7,000 ft) a.s.l., or about 900 m above the summit, and drifted E. 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.
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC)

Report for Ebeko
According to the Tokyo VAAC a possible ash plume at Ebeko was visible in a satellite image at 0920 on 14 April rising to 2.4 (8,000 ft) a.s.l. and drifted NE. The plume had dissipated by 1120. Another plume from a possible eruption was identified in satellite images at 1300, rising to 3.7 (12,000 ft) a.s.l. and drifting N. The plume was no longer visible or had dissipated by 1720. At 1452 on 16 April an ash plume rose to 3 km (10,000 ft) a.s.l. and drifted NE.
Source: Tokyo Volcanic Ash Advisory Center (VAAC)

Report for Fuego
INSIVUMEH reported that 4-13 explosions per hour were generally recorded at Fuego during 11-18 April, generating daily ash plumes that rose as high as 1.7 km above the crater rim and drifted as far as 30 km SW, S, SE, and E. Daily ashfall was recorded in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), La Rochela, San Andrés Osuna, Ceylon, Finca La Asunción, El Zapote (10 km S), Alotenángo (8 km ENE), and other areas to the N and NE. Daily block avalanches descended multiple drainages including the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Honda, Las Lajas (SE), and El Jute (ESE), and often reached vegetated areas. Daily shock waves rattled structures in communities around the volcano and rumbling was often heard. Explosions ejected incandescent material as high as 350 m above the summit on most days.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Report for Great Sitkin
AVO reported that lava continued to slowly erupt at the summit of Great Sitkin during 11-17 April, producing a thick lava flow that expanded mostly to the E. Seismicity was low, and during 11-13 April only a few small events were detected. Elevated surface temperatures were identified in satellite images during 16-17 April, and steam emissions were visible in webcam views during 17-18 April. Weather clouds often obscured satellite and webcam views during most 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 color on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Ibu
PVMBG reported that the eruption at Ibu continued during 12-18 April. White-and-gray plumes of variable densities rose as high as 800 m above the summit and drifted NE, S, SW, and NW. The Alert Level remained at a 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Report for Karangetang
Webcam images of Karangetang captured in the PVMBG daily reports periodically showed small areas of incandescence at the summit craters during 11-17 April. 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.
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 12-17 April. White steam-and-gas plumes of variable densities were seen on most days rising as high as 700 m above the summit and drifting NE, E, and SE. On 13, 15, and 17 April white-and-gray plumes rose as high as 500 m and drifted NW, NE, E, and SE. 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 7-13 April and seismicity remained at high levels. The SW lava dome produced 132 lava avalanches that traveled as far as 2 km down the SW flank (upstream in the Bebeng and Boyong drainages). Morphological changes to the SW lava dome were evident in webcam images 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 Rincon de la Vieja
OVSICORI-UNA reported that small phreatic eruptions, often in association with observed emissions, occurred at Rincón de la Vieja during 11-17 April. A small phreatic eruption on 11 April consisted of several pulses of activity recorded during 0653-0700 and at 0743. Gas-and-steam plumes rose 500 m above the crater rim. A small phreatic event was recorded late in the evening. An event at 0450 on 12 April produced a gas-and-steam plume that rose 500 m and another was recorded at 1920 with no visual observations reported. Gas-and-steam emissions from a phreatic event were seen at 0632 on 13 April; an event was recorded at 1826 with no visual observations reported. At 0936 on 14 April an event produced a gas-and-steam plume that rose as high as 2 km and was seen from Curubandé. The event was preceded by a swarm of long-period earthquakes five hours prior to the eruption; sediments were possibly ejected from the crater lake and deposited on the crater floor. A small phreatic eruption at 0647 on 16 April ejected material out of the crater and produced a gas-and-steam plume that rose 2 km. A smaller emission rose 500 m at 0957 and at 2235 an event generated a plume that rose 500 m. At 1237 on 17 April a phreatic event produced a plume that rose 1.5 km above the crater rim and a brief event was recorded at 0722 on 18 April.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

Report for Sabancaya
Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 10-16 April with a daily average of 41 explosions. Gas-and-ash plumes rose as high as 2.5 km above the summit and drifted NW, W, SW, and S. Six thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. 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 Santa Maria
INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 12-18 April. 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. Incandescence from the dome and the lava flows was frequently visible at night. Avalanches down the N, E, S, and SW flanks of the dome were sometimes generated from the lava-flow front and margins. Daily weak or weak-to-moderate explosions were recorded by the seismic network and on most days the explosions generated ash plumes that rose as high as 1 km above the complex and drifted mainly E, S, and SW. Weak rumbling was barely heard on nearby farms during 16-17 April. Residents were reminded to stay at least 6 km away from the complex.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Report for Semeru
PVMBG reported that the eruption at Semeru continued during 12-18 April and daily Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued through the week. At 0747 on 12 April a dense white-to-gray plume rose 600 m above the summit and drifted N. On 13 April at 1135 a gray-to-brown ash plume rose 400 m and drifted NE, at 1249 a dense gray ash plume rose 500 m and drifted N and NE, and at 1709 a dense white-to-gray ash plume rose 600 m and drifted E. At 0529 on 14 April a white-to-brown ash plume rose 500 m and drifted S. White-to-gray ash plumes at 0606 and 0731 on 15 April rose 600-700 m and drifted N and NE. At 0551 on 16 April a dense white-to-gray ash plume rose 1 km and drifted N. On 17 April at 0614 a medium-density white-to-brown ash plume rose 700 m and drifted S and at 0847 a white-to-gray ash plume rose 600 m and also drifted S. At 0540 and 0708 on 18 April dense white-to-gray ash plumes rose 500-600 m and drifted S and W. The Alert Level remained at 3 (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 originating on Semeru, 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 12-18 April. No eruptive activity was observed, though some weak seismicity was recorded. Cloudy weather often prevented webcam and satellite views during most 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 color on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)

Report for Suwanosejima
JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 10-17 April. Eruptive activity produced ash plumes during 12-14 and 17 April that rose as high as 1.5 km above the crater rim and drifted NW, S, SE, and E. Large blocks were ejected as far as 500 m from the vent. Crater incandescence was visible nightly. 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)