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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 18 April-24 April 2007
Name Location Eruption Start Date Report Status
Concepcion Nicaragua New
Lopevi Vanuatu New
Nevado del Huila Colombia New
Piton de la Fournaise Reunion Island (France) New
Anatahan Mariana Islands (USA) Continuing
Bulusan Luzon (Philippines) Continuing
Chikurachki Paramushir Island (Russia) Continuing
Fuego South-Central Guatemala 2002 Jan 4 Continuing
Karymsky Eastern Kamchatka (Russia) Continuing
Kilauea Hawaiian Islands (USA) Continuing
Klyuchevskoy Central Kamchatka (Russia) 2023 Jun 22 Continuing
Rabaul New Britain (Papua New Guinea) Continuing
Reventador Ecuador 2008 Jul 27 Continuing
Santa Maria Southwestern Guatemala 1922 Jun 22 Continuing
Sheveluch Central Kamchatka (Russia) 1999 Aug 15 Continuing
Soufriere Hills Montserrat Continuing
St. Helens Washington Continuing
Tungurahua Ecuador Continuing
Ubinas Peru Continuing
All times are local unless otherwise stated.
Weekly Reports Archive

Since the Weekly Volcanic Activity Report began in November 2000, there have been 19,934 individual reports over 1,212 weeks (average of 16 per week) on 332 different volcanoes.

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

Report for Concepcion
INETER reported that explosions in the crater of Concepción on 22 April produced ash-and-gas plumes that drifted WSW.
Source: Instituto Nicaragüense de Estudios Territoriales (INETER)
Report for Lopevi
Based on pilot reports and satellite imagery, the Wellington VAAC reported that ash plumes from Lopevi rose to altitudes of 2.4-4.6 km (8,000-15,000 ft) a.s.l. during 21-24 April. Plumes drifted E on 21 April.
Source: Wellington Volcanic Ash Advisory Center (VAAC)
Report for Nevado del Huila
Based on satellite imagery, the Washington VAAC reported that an ash eruption from Nevado del Huila on 18 April produced a plume that drifted SW and dissipated. On 22 April, INGEOMINAS reported that during aerial observations, fumarolic activity was observed from a fissure first noted on 19 February. The fissure was approximately 2.3 km long and 0.2 km wide. A resultant plume rose to an altitude of 10.4 km (34,100 ft) a.s.l. Another fissure, extending about 2 km from the SW to the NE sector of Pico Central, also produced fumarolic emissions. Mudflows in the Páez and Símbola rivers originating on Pico Central primarily swept through the Oso ravine on the E flank and Bellavista ravine on the W flank.

According to news articles, the eruption during 17-18 April caused damage to houses and destroyed 19 bridges along the Páez and Símbola rivers. Several kilometers of a highway, used to transport goods and medicines to the population, were also destroyed. INGEOMINAS noted that there were no reported deaths or injuries as a result of the eruption.
Sources: Associated Press, Associated Press, Servicio Geológico Colombiano (SGC), Washington Volcanic Ash Advisory Center (VAAC)
Report for Piton de la Fournaise
OVPDLF reported that the eruption of Piton de la Fournaise from the S-part of the Grand Brûlé continued during 18-24 April. Tremor in this area remained very low throughout the reporting period. On 22 April, a large plume was visible from where lava flows met the sea. On 23 April, abundant lava flows in Grand Brûlé traveled in lava tubes. A collapsed lava-tube ceiling resulted in the formation of a hornito.
Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)
Report for Anatahan
Based on satellite imagery and aerial observation on 15 April, Anatahan's crater lake emitted diffuse steam-and-gas plumes. Tremor increased and remained elevated on 20 April.
Source: Emergency Management Office of the Commonwealth of the Mariana Islands and United States Geological Survey Volcano Hazards Program
Report for Bulusan
PHIVOLCS reported on 17 April that seismicity from Bulusan increased significantly during 16-17 April. Ground deformation surveys conducted in March and April indicated 4 mm of inflation on the NNE flank. Steam plumes from the crater and fissures rose to altitudes of 1.8 km (5,900 ft) a.s.l. and drifted WSW.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
Report for Chikurachki
KVERT reported that bursts of volcanic bombs from Chikurachki were observed by hunters on 15 April. Ash plumes were seen on satellite imagery drifting SE on 14 April and WNW during 15-16 April. Ash plumes rose to altitudes of 3.8 km (12,500 ft) a.s.l. and drifted N on 18 April. The Level of Concern Color Code remained at Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Report for Fuego
INSIVUMEH reported that on 20 and 23 April, Strombolian activity was observed at Fuego; incandescent material was ejected about 50-75 m above the summit and blocks descended 300 m down the S and W flanks. On 20 April, sounds resembling locomotives accompanied the eruption, and lava overflowed the crater on the S flank and traveled 100 m. The Washington VAAC reported that an intense hotspot seen on satellite imagery on 21 April was likely caused by a lava flow to the SW, according to information from INSIVUMEH. A plume drifting SW was also visible on satellite imagery and may have been a result of fires started by lava flows; the plume may have also contained light ash and gas. On 23 April, INSIVUMEH reported that pyroclastic flows and incandescent avalanches traveled down SE and SW ravines. Ash explosions caused light ashfall in areas S of the volcano and fumarolic and gas plumes rose to an altitude of 4 km (13,000 ft) a.s.l.
Sources: Washington Volcanic Ash Advisory Center (VAAC), Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
Report for Karymsky
Seismic activity at Karymsky was above background levels during 13-20 April. Ash plumes from explosions occurred during 13-20 April and may have reached altitudes of 4 km (13,000 ft) a.s.l. during 15-16 April and drifted E. Based on visual observation, a gas-and-steam plume rose to an altitude of 2.5 km (8,200 ft) a.s.l. on 19 April and a possible new lava flow was seen on the SW flank. A thermal anomaly in the crater was detected on satellite imagery during 14-16 April. Based on pilot reports, satellite imagery, and observations in the Petropavlovsk-Kamchatsky Flight Information Region (FIR), the Tokyo VAAC reported that an ash plume rose to an altitude of 7.6 (25,000 ft) a.s.l. and drifted SE. The Level of Concern Color Code remained at Orange.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)
Report for Kilauea
During 18-24 April, lava from Kilauea continued to flow SE across a lava delta into the ocean at the Kamokuna entry, but lava was not seen entering the ocean at East Lae'apuki. Incandescence was intermittently visible from several breakouts on the Pulama pali and from several vents in the Pu'u 'O'o crater. Earthquake activity was scattered at the summit and S-flank areas. Tremor remained at moderate levels.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Report for Klyuchevskoy
During 13-20 April, Strombolian activity occurred at Kliuchevskoi, based on observations and video data. Seismic activity continued above background levels and a thermal anomaly in the crater was detected on satellite imagery. Fumarolic activity intensified during 15 and 17-18 April. Gas-and-steam plumes possibly containing small amounts of ash rose to altitudes of 6.3-7.2 km (20,700-23,600 ft) a.s.l. during 15 and 17-18 April and drifted in multiple directions. Based on pilot reports, satellite imagery, and observations in the Petropavlovsk-Kamchatsky Flight Information Region (FIR), the Tokyo VAAC reported several E-drifting ash plumes. They rose to altitudes of 5.2 (17,000 ft) a.s.l. and 8.8 km (29,000 ft) on 18 and 22 April, respectively. On 24 April, KVERT reported mudflows and phreatic activity at lava flow fronts on the NW flank. Resultant ash plumes rose from the lava flow fronts to an altitude of 3.5 km (11,500 ft) a.s.l. The Level of Concern Color Code remained at Orange.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Kamchatkan Volcanic Eruption Response Team (KVERT)
Report for Rabaul
RVO reported that during 16-25 April, white-to-gray emissions from Rabaul caldera's Tavurvur cone generated plumes that rose a few hundred meters and drifted multiple directions. Based on reports from RVO and satellite imagery, the Darwin VAAC reported that a diffuse plume rose to an altitude of 1.5 km (5,000 ft) a.s.l. on 18 April and drifted SW. Occasionally during 18-23 April, moderately-sized explosions led to darker gray plumes. During 22-25 April, light ashfall was reported in Rabaul town. Weak roaring noises occasionally accompanied the emissions. A slight glow was seen from crater at night and small amounts of incandescent material were rarely ejected from the crater during 16-23 April.
Sources: Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC)
Report for Reventador
On 18, 20, and 23 April, steam-and-gas emissions from Reventador hung near the summit. On 18 April, a plume was seen drifting NW on satellite imagery. On 20 April, a bluish haze of gases was observed. Clouds occasionally inhibited views of the summit during 18-24 April.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)
Report for Santa Maria
INSIVUMEH reported that explosions from Santa María's Santiaguito lava dome complex on 20 and 23 April occasionally produced ash plumes that rose to altitudes of 5.3 km (17,400 ft) a.s.l. The plumes drifted SW and ashfall was reported from areas up to 9 km to the SW. On 23 April, lava flows on the SW and NE flanks of Caliente dome produced small landslides composed of blocks.

Based on satellite imagery, the Washington VAAC reported that diffuse ash plumes on 18, 23, and 24 April, and gas plumes possibly containing ash on 20 April, drifted SW and W.
Sources: Washington Volcanic Ash Advisory Center (VAAC), Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
Report for Sheveluch
KVERT reported that seismic activity at Shiveluch continued above background levels during 13-20 April. Based on seismic interpretation, observation, and video data, ash-and-steam plumes possibly rose to altitudes of 5.5-6.5 km (18,000-21,300 ft) a.s.l. throughout the reporting period. Plumes were seen on satellite imagery drifting E, SE, and S and a thermal anomaly was present. Base on pilot reports, satellite imagery, KEMSD, and observations from the Petropavlovsk-Kamchatsky Flight Information Region (FIR), the Tokyo VAAC reported that ash plumes rose to altitudes of 4.6-6.1 km (15,000-20,000 ft) a.s.l. during 18-22 April. They drifted E. The Level of Concern Color Code remained at Orange.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)
Report for Soufriere Hills
During 13-20 April, visual observations suggested that lava-dome growth at Soufrière Hills continued at a reduced rate. Material originating from the lava dome's growing E-facing shear lobe was shed down the Tar River Valley. Heavy rains resulted in lahars in several drainages 16-17 April. During 18-20 April, a gas plume drifted N and NE and a bluish haze containing sulfur dioxide was observed flowing down the N flanks due to light winds coming from the S.
Source: Montserrat Volcano Observatory (MVO)
Report for St. Helens
Data from deformation-monitoring instruments and observations from a remote camera showed that during 18-24 April lava-dome growth at Mount St. Helens continued. Seismicity persisted at low levels, punctuated by M 1.5-2.5, and occasionally larger, earthquakes. In some instances, clouds inhibited visual observations.
Source: US Geological Survey Cascades Volcano Observatory (CVO)
Report for Tungurahua
IG reported that during 17-18 April, Strombolian activity from Tungurahua was observed; incandescent material was ejected about 500 m above the summit and blocks descended down the flanks. Lahars carring large blocks NW down the Mandur gorge caused a road closing on 19 April. During 17-24 April, ash plumes rose to altitudes of 5.5-9 km (18,000-29,500 ft) a.s.l. and drifted W and N. Ashfall was reported from areas mainly to the N, NW, W, and SW during 17, 19, 21-22, and 24 April. On 23 April, lahars were observed in several gorges to the NW. Clouds occasionally inhibited views of the summit during the reporting period.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)
Report for Ubinas
INGEMMET reported that on 18 April, explosions from Ubinas produced gas and ash plumes to altitudes of 5.9-7.7 km (19,400-25,300 ft) a.s.l. Plumes drifted SW. Based on significant meteorological (SIGMET) notices, satellite imagery, and pilot reports, the Buenos Aires VAAC reported that ash plumes rose to altitudes of 5.5-7 km (18,000-28,000 ft) a.s.l. on 17, 18, 22, and 24 April. Plumes drifted NW, SW, and SE.
Sources: Buenos Aires Volcanic Ash Advisory Center (VAAC), Instituto Geológico Minero y Metalúrgico (INGEMMET)