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Smithsonian / USGS Weekly Volcanic Activity Report

Weekly Volcanic Activity Map

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

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

Smithsonian / USGS Weekly Volcanic Activity Report for the week of 19 April-25 April 2023
Name Country Volcanic Province Eruption Start Date Report Status
Bezymianny Russia Eastern Kamchatka Volcanic Arc 2022 Mar 15 New
Nevado del Ruiz Colombia Northern Andean Volcanic Arc 2014 Nov 18 New
Rincon de la Vieja Costa Rica Central America Volcanic Arc 2021 Jun 28 New
Sheveluch Russia Eastern Kamchatka Volcanic Arc 1999 Aug 15 New
Ahyi United States Mariana Volcanic Arc — Continuing
Aira Japan Ryukyu Volcanic Arc 2017 Mar 25 Continuing
Ambae Vanuatu Vanuatu Volcanic Arc — Continuing
Cotopaxi Ecuador Northern Andean Volcanic Arc — Continuing
Ebeko Russia Kuril Volcanic Arc 2022 Jun 11 Continuing
Fuego Guatemala Central America Volcanic Arc 2002 Jan 4 Continuing
Great Sitkin United States Aleutian Ridge Volcanic Arc 2021 May 25 Continuing
Karangetang Indonesia Sangihe Volcanic Arc — Continuing
Katmai United States Alaska Peninsula Volcanic Arc — Continuing
Lewotolok Indonesia Sunda Volcanic Arc — Continuing
Merapi Indonesia Sunda Volcanic Arc 2020 Dec 31 Continuing
Reventador Ecuador Northern Andean Volcanic Arc 2008 Jul 27 Continuing
Sabancaya Peru Central Andean Volcanic Arc 2016 Nov 6 Continuing
Santa Maria Guatemala Central America Volcanic Arc 1922 Jun 22 Continuing
Semeru Indonesia Sunda Volcanic Arc 2017 Jun 6 Continuing
Semisopochnoi United States Aleutian Ridge Volcanic Arc — Continuing
Suwanosejima Japan Ryukyu Volcanic Arc 2004 Oct 23 Continuing
All times are local unless otherwise stated.
Weekly Reports Archive

Since the Weekly Volcanic Activity Report began in November 2000, there have been 20,652 individual reports over 1,244 weeks (average of 17 per week) on 338 different volcanoes.

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Adams Cotopaxi Iliwerung Llaima Popocatepetl Sumisujima
Agung Cuicocha Inielika Lokon-Empung Purace Sundoro
Ahyi Cumbal Ioto Lonquimay Puyehue-Cordon Caulle Suoh
Aira Dabbahu Irazu Lopevi Rabaul Suretamatai
Akan Davidof Iwatesan Machin Raikoke Suwanosejima
Alaid Dempo Iya Makushin Ranakah Taal
Alu-Dalafilla Descabezado Grande Izu-Torishima Maly Semyachik Raoul Island Tair, Jebel at
Ambae Dieng Volcanic Complex Jackson Segment Manam Rasshua Takawangha
Ambang Dukono Kaba Manda Hararo Raung Talang
Ambrym East Epi Kadovar Marapi Redoubt Tambora
Anatahan Ebeko Kaitoku Seamount Maroa Reventador Tanaga
Aniakchak Ebulobo Kama'ehuakanaloa Martin Reykjanes Tandikat-Singgalang
Antillanca Volcanic Complex Edgecumbe Kambalny Masaya Rincon de la Vieja Tangkoko-Duasudara
Antuco Egon Kanaga Matthew Island Rinjani Tangkuban Parahu
Apoyeque Ekarma Kanlaon Maule, Laguna del Ritter Island Tara, Batu
Arenal Eldey Karangetang Mauna Loa Rotorua Ta'u
Asamayama Erebus Karkar Mayon Ruang Taupo
Askja Erta Ale Karthala McDonald Islands Ruapehu Telica
Asosan Etna Karymsky Melebingoy Ruby Tenerife
Atka Volcanic Complex Etorofu-Yakeyama [Grozny Group] Kasatochi Melimoyu Ruiz, Nevado del Tengger Caldera
Augustine Eyjafjallajokull Katla Merapi Sabancaya Three Sisters
Avachinsky Fagradalsfjall Katmai Midagahara Sakar Tinakula
Awu Fernandina Kavachi Misti, El Salak Tofua
Axial Seamount Fogo Kelimutu Miyakejima San Cristobal Tokachidake
Azul, Cerro Fonualei Kelud Momotombo San Miguel Tolbachik
Azumayama Fournaise, Piton de la Kerinci Monowai San Vicente Toliman
Bagana Fourpeaked Ketoi Montagu Island Sangay Tongariro
Balbi Fuego Kharimkotan Moyorodake [Medvezhia] Sangeang Api Trident
Bamus Fujisan Kick 'em Jenny Mutnovsky Santa Ana Tungurahua
Banda Api Fukutoku-Oka-no-Ba Kie Besi Myojinsho Santa Maria Turrialba
Bardarbunga Galeras Kikai Nabro Sao Jorge Ubinas
Barren Island Galunggung Kilauea Negra, Sierra Sarigan Ugashik-Peulik
Batur Gamalama Kirishimayama Negro, Cerro Sarychev Peak Ukinrek Maars
Bezymianny Gamkonora Kita-Ioto Nightingale Island Saunders Ulawun
Bogoslof Gareloi Kizimen Nishinoshima Savo Unnamed
Brava Gaua Klyuchevskoy Nisyros Semeru Unnamed
Bristol Island Gorely Kolokol Group Novarupta Semisopochnoi Veniaminof
Bulusan Great Sitkin Koryaksky NW Rota-1 Seulawah Agam Villarrica
Calbuco Grimsvotn Krakatau Nyamulagira Sheveluch Vulcano
Callaqui Guagua Pichincha Krummel-Garbuna-Welcker Nyiragongo Shishaldin West Mata
Cameroon Guallatiri Krysuvik-Trolladyngja Ofu-Olosega Simbo Westdahl
Campi Flegrei Guntur Kuchinoerabujima Okataina Sinabung Whakaari/White Island
Campi Flegrei del Mar di Sicilia Hachijojima Kurikomayama Okmok Sinarka Witori
Cayambe Hakoneyama Kusatsu-Shiranesan Ontakesan Siple Wolf
Chachadake [Tiatia] Heard Kverkfjoll Oraefajokull Sirung Wrangell
Chaiten Hekla La Palma Osorno Slamet Yakedake
Chiginagak Helgrindur Lamington Pacaya Snaefellsjokull Yasur
Chikurachki Hierro Lamongan Pagan Soputan Yellowstone
Chiles-Cerro Negro Hokkaido-Komagatake Langila Palena Volcanic Group Sorikmarapi Yufu-Tsurumi
Chillan, Nevados de Home Reef Lanin Paluweh Sotara Zaozan [Zaosan]
Chirinkotan Hood Lascar Panarea Soufriere Hills Zavodovski
Chirpoi Huaynaputina Late Papandayan Soufriere St. Vincent Zhupanovsky
Ciremai Hudson, Cerro Lateiki Pavlof South Sarigan Seamount Zubair Group
Cleveland Huila, Nevado del Lengai, Ol Doinyo Pelee Spurr
Colima Hunga Tonga-Hunga Ha'apai Leroboleng Peuet Sague St. Helens
Colo Ibu Lewotobi Pinatubo Stromboli
Concepcion Ijen Lewotolok Planchon-Peteroa Sulu Range
Copahue Iliamna Little Sitkin Poas Sumbing
 News Feeds and Google Placemarks


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The RSS (Really Simple Syndication) feed is identical to the Weekly Volcanic Activity Report minus some features including the header information (latitude and longitude and summit elevation), the Geologic Summary, and a link to the volcano's page from the Global Volcanism Program. At the end of each report is a list of the sources used. Each volcano report includes a link from the volcano's name back to the more complete information in the Weekly Volcanic Activity Report on the Smithsonian website. This feature was first made available on 5 March 2008.


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A Google Earth network link for the Weekly Volcanic Activity Report can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano profile page and to the complete Weekly Report for that week. This feature was first made available on 1 April 2009.

 Criteria & Disclaimers

Criteria



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

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

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

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

Disclaimers



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

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

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

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

5. USGS Disclaimer Statement for this Website:

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

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

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

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

 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)

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Report for Bezymianny
KVERT reported that a daily thermal anomaly from continuing lava effusion at Bezymianny was identified in satellite images during 14-20 April. Gas-and-steam emissions were visible and occasional collapses from the growing lava dome produced avalanches of hot material. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale) on 20 April because activity had declined after the strong 7-8 April explosive eruption. Dates are based on UTC times; specific events are in local time where noted.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Report for Nevado del Ruiz
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that the eruption at Nevado del Ruiz continued during 18-25 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 were located 1-3 km W, SW, NE, and E of Arenas Crater and below the crater, at depths of 0.4-6.2 km. The largest event, a M 1.7, was recorded at 1735 on 24 April and was located 4.1 km E of the crater, at a depth of 3.2 km. The event was felt by residents in the Lagunilla river canyon. Additionally, signals indicating fluid movement fluctuated in intensity and were associated with daily gas-and-steam emissions, sometimes containing ash, that rose as high as 1.8 km above the crater rim. At 0711 on 18 April an ash plume rose 1.8 km above the crater rim and drifted SE, causing ashfall in the municipality of Anzoátegui, Tolima. At 2235 on 19 April and at 2248 on 21 April ash plumes rose 1.8 km and drifted SSE. Gas emissions with possible ash rose as high as 1.3 km and drifted SW and E during 20-21 April. Pulsating ash emissions were seen in webcam images during 23-25 April. The Alert Level remained at Orange, Level II (the second highest level on a four-level scale).
Source: Servicio Geológico Colombiano (SGC)
Report for Rincon de la Vieja
OVSICORI-UNA reported that phreatic eruptions, detected seismically but often with observed emissions, continued to occur at Rincón de la Vieja during 18-25 April. Several eruptive events recorded during 18-21 April produced gas-and-steam emissions that rose as high as 1.5 km above the crater rim. A strong eruptive event at 1550 on 21 April generated a dense plume of material that rose 500 m above the crater rim and then collapsed, producing a pyroclastic flow and lahars on the N flank. A steam-and-gas plume with minor ash content rose 4-5 km above the crater rim. Strong tremor levels and near-continuous gas emissions were recorded after the event. That same day OVSICORI-UNA noted that during the previous week sulfur dioxide emissions were 221 tons per day on average, though emissions spiked to close to 5,000 tons per day after several of the phreatic events. During 22-24 April nearly continuous gas emissions continued to be visible and strong tremor continued to be recorded by the seismic network. Small phreatic events were recorded at 1904 on 22 April and at 0054 and 0629 on 24 April. Small phreatic events at 2250 on 23 April and 0630 on 24 April produced steam-and-gas plumes that rose no higher than 500 m above the crater rim.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)
Report for Sheveluch
KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 14-20 April. During 14-15 April ash plumes rose to 6 km (19,700 ft) a.s.l. and drifted 700 km NW. During 17-19 April plumes of unconsolidated ash resuspended from the flanks by wind rose to 4 km (13,100 ft) a.s.l. and drifted as far as 224 km NW. The sulfur dioxide gas portion of the eruption cloud produced during the notable 11-12 April activity continued to drift E; by 21 April the leading edge of the plume was over part of Greenland. 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 Ahyi
On 26 April both the Aviation Color Code and the Volcano Alert Level for Ahyi Seamount were lowered to Unassigned because signs of unrest had decreased, and no indication of submarine volcanic activity had occurred for at least four weeks. Observations of discolored water near the seamount were last identified in satellite images in late March 2023, and underwater activity based on acoustic signals had been negligible since early April 2023.
Source: US Geological Survey
Report for Aira
JMA reported ongoing eruptive activity at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 17-24 April, with crater incandescence visible nightly. Two eruptive events on 17 April produced ash plumes that rose 1-1.5 km and drifted S. That same day sulfur dioxide emissions were somewhat high at 1,900 tons per day. Very small eruptive events occasionally occurred during 21-24 April. 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 Ambae
Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that at 0730 on 19 April a plume consisting of steam, sulfur dioxide gas, and ash rose 695 m above Ambae’s summit and drifted E and SE, based on an image from a webcam located 22 km NE on the NE tip of Ambae Island, in Saratamata. The Alert Level remained at 2 (on a scale of 0-5) and the public was warned to stay outside of the Danger Zone, defined as a 2-km radius around the active vents in Lake Voui, and away from drainages during heavy rains.
Source: Vanuatu Meteorology and Geohazards Department (VMGD)
Report for Cotopaxi
IG reported ongoing moderate eruptive activity at Cotopaxi during 18-25 April. Cloudy weather sometimes prevented webcam and satellite views, but daily emissions of steam-and-gas rising as high as 1.5 km were seen in webcam images. Small ash-and-gas emissions were visible during 21-22 April. An ash plume first seen at 0953 on 24 April rose up to 3 km above the summit and drifted NE. Later that afternoon and evening ash-and-gas emissions rose 350 m and drifted N. At 1600 the seismic station recorded a small secondary lahar that descended the Cutzalao/Agualongo drainage on the SW 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 Ebeko
KVERT reported that moderate activity at Ebeko was ongoing during 13-20 April and a thermal anomaly was identified in satellite images during 14-15 April. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), and satellite data, explosions during 14-16 April generated ash plumes that rose as high as 3.5 km (11,500 ft) a.s.l. and drifted 104 km NE. Weather clouds prevented satellite views on the other days of the week. 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 Fuego
INSIVUMEH reported that 4-12 explosions per hour were recorded at Fuego during 18-25 April, generating daily ash plumes that rose as high as 1 km above the crater rim and drifted as far as 65 km SW, S, SE, and E. Ashfall was recorded each day in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), La Rochela, Santa Sofía (12 km SW), San Andrés Osuna, Ceilan, Finca La Asunción, Ceylon, El Zapote (10 km S), Aldeas, El Rodeo and other nearby communities. Daily block avalanches descended multiple drainages including the Santa Teresa, 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. During 22-23 April the avalanches remobilized ash deposits causing a plume that rose 100 m and drifted S and SE. On 23 April lahars in the Ceniza drainage carried branches, tree trunks, and blocks 30 cm to 1.5 m in diameter.
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 19-25 April. Weather clouds often obscured satellite and webcam views during most of the week. Seismicity was low, and during 21-22 April only a few small events were detected. Satellite data last acquired on 14 April showed that the thick lava continued to expand towards the E and remained confined to the summit crater. 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 Karangetang
PVMBG reported that the effusive eruption which began around 1700 on 8 February at Karangetang’s Main Crater (S crater) produced lava flows and lava avalanches that traveled as far as 2 km down the SW and S flanks in drainages leading to the Beha, Batang, Timbelang, Batuawang, and Kahetang rivers. Effusion ended on 1 April and avalanches of material were no longer detected. Seismic signals indicating effusion decreased and by 6 April were no longer being detected. Incandescence at both Main Crater and Crater II (N crater) was visible at night during 1-25 April. White gas plumes were seen rising as high as 200 m above the summit and drifted in multiple directions; weather clouds sometimes prevented views. On 26 April the Alert Level was lowered to 2 (on a scale of 1-4) and the public was warned to stay 2.5 km away from the craters on the S and SW flanks and 1.5 km away on the other flanks.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Report for Katmai
AVO reported that during the morning of 23 April, strong NW winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes dispersed unconsolidated ash up to 1.8 km (6,000 ft) a.s.l. to the SE across Shelikof Strait to Kodiak Island. The ash was originally deposited during the Novarupta-Katmai eruption in 1912. The Volcano Alert Level remained at Normal (the lowest level on a four-level scale) and the Aviation Color Code remained at Green (the lowest level on a four-color scale).
Source: US Geological Survey Alaska Volcano Observatory (AVO)
Report for Lewotolok
PVMBG reported that the eruption at Lewotolok was ongoing during 19-25 April. On 19, 21, and 23 April white-and-gray plumes rose 200-700 m and drifted E, NE, N, and NW. White steam-and-gas plumes of variable densities were seen during 20, 22, and 24-25 April rising as high as 500 m above the summit and drifting SW, W, and NW. Crater incandescence was visible in webcam images posted with the reports during 21-22 April. 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 19-25 April and seismicity remained at high levels. The SW lava dome produced more than 80 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 Reventador
IG reported that the eruption at Reventador was ongoing during 19-25 April. Seismic activity was not characterized due to technical problems. Steam, gas, and ash plumes were observed in IG webcam images and described in Washington VAAC advisories on most days; weather conditions occasionally prevented views. The plumes rose as high as 1.6 km above the summit and drifted E, SE, W, and SW. Crater incandescence was visible at night during 20-21 April. 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 Sabancaya
Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 17-23 April with a daily average of 31 explosions. Gas-and-ash plumes rose as high as 1.6 km above the summit and drifted NE, E, SW, and W. Fourthermal 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 18-25 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. Daily avalanches descended multiple flanks of the dome and were also occasionally generated from the lava-flow front and margins. Daily weak or weak-to-moderate explosions recorded by the seismic network generated ash plumes that rose as high as 1 km above the complex and drifted mainly S and SW. During 18-19 April ash fall was reported in Finca El Faro (6.7 km S). On 21 April quiet rumbling sounds were barely heard on nearby farms. Residents were reminded to stay away from the lava flow and at least 6 km away from the dome complex.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
Report for Semeru
PVMBG reported that the eruption at Semeru continued during 18-25 April and frequent Volcano Observatory Notices for Aviation (VONAs) describing ash emissions were issued through the week. On 19 April at 0710 and 0829 dense white-and-gray ash plumes rose 800-1,000 m above the summit and drifted S. On 20 April at 0616, 0619, 0805, and 0902 white-and-gray variable density ash plumes rose 300-1,000 m and drifted N and NW. At 0534 on 21 April a white-to-brown ash plume rose 600 m and drifted NE and at 0640 a dense white-and-gray ash plume rose 700 m and drifted SW. On 23 April at 0448, 0553, 0643, and 0731 gray ash plumes of variable densities rose 400-1,000 m and drifted SE, S, SW, and W. On 25 April at 0519, 0710, and 0756 dense gray ash plumes rose 500-800 m and drifted NW, W, and SW. 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 18-25 April. Daily periods or bursts of tremor and occasional low-frequency earthquakes were detected during the week. Small explosions were detected in seismic and infrasound data during 18-19 and 24-25 April. Cloudy weather prevented webcam and satellite views on most days. Possible recent ash deposits on Mount Young’s crater rim were visible in clear webcam images during 22-23 April, and steam emissions from the active N crater were visible during 22-25 April. 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 17-24 April. No explosions were recorded, but eruptive activity produced periodic ash plumes and ejected blocks as far as 300 m from the vent. On 17 April ash plumes rose 1-1.5 km above the crater rim and drifted E and SE, and on 18 April an ash plume rose 2 km and drifted N. Ashfall was reported in Toshima village (3.5 km SSW) during 17-21 April. On 23 April an ash plume rose 1.1 km and drifted SW. 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)