All times are local unless otherwise stated.

Asosan | 25 May-31 May 2011 | New Activity / Unrest Cite this Report
Asosan Kyushu (Japan)	Based on notices from JMA, the Tokyo VAAC reported that during 25, 27-28, and 31 May ash plumes from Aso rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted NW, N, E, and S. Source: Tokyo Volcanic Ash Advisory Center (VAAC)
Dieng Volcanic Complex | 25 May-31 May 2011 | New Activity / Unrest Cite this Report
Dieng Volcanic Complex Central Java	CVGHM reported that on 29 May gas plumes rose 50 m above Timbang, a cone that is part of the Dieng Volcanic Complex. The gas plumes drifted S through the valley. Observers who visited the cone noted damaged vegetation and dead birds. Seismicity and carbon dioxide gas emissions remained elevated. CVGHM raised the Alert Level to 3 (on a scale of 1-4). According to news articles, about 1,200 people were evacuated from the flanks. Sources: People's Daily Online (China), Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Grimsvotn | 25 May-31 May 2011 | New Activity / Unrest Cite this Report
Grimsvotn Iceland	According to scientists from the Institute of Earth Sciences at the University of Iceland and the Icelandic Meteorological Office, explosive activity occurred from four tephra cones surrounded by water in Grímsvötn's crater during the evening of 24 May. Pulsating ash plumes rose a few kilometers above the cones, producing only local fallout of material. Seismic tremor decreased. On 25 May, observers noted steam bursts from the crater. Tephra fallout was noted only in the vicinity of the eruption site. Pilots reported widespread ash in layers 5-7 km W of the volcano and also some ash haze below 3 km (9,800 ft) a.s.l. to the SW. Seismic tremor decreased considerably. On 26 May minor steam explosions continued from the crater. According to news articles, air traffic disruption was reduced to parts of Norway and Sweden. On 28 May tremor rapidly decreased then disappeared, and on 30 May participants on the Iceland Glaciological Society's spring expedition confirmed that the eruption had ended. Satellite imagery and visual observations showed that only small amounts of ice melted during the eruption; no signs of flooding had been detected. Sources: Agence France-Presse (AFP), Institute of Earth Sciences, Icelandic Meteorological Office (IMO)
Klyuchevskoy | 25 May-31 May 2011 | New Activity / Unrest Cite this Report
Klyuchevskoy Central Kamchatka (Russia)	Based on video data and ground-based observations, KVERT reported that on 29 May an ash plume from Kliuchevskoi rose to an altitude of 5 km (16,400 ft) a.s.l. and drifted SW. The Aviation Color Code was raised to Orange. No activity was noted on 30 May and the volcano was obscured by clouds the next day. The Aviation Color Code was lowered to Yellow. Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Aira | 25 May-31 May 2011 | Continuing ActivityCite this Report
Aira Kyushu (Japan)	Based on information from JMA, the Tokyo VAAC reported that during 25-30 May explosions from Sakura-jima frequently produced plumes that rose to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. Plumes drifted N, NW, E, SE, and S. On 27 May, a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted E. Source: Tokyo Volcanic Ash Advisory Center (VAAC)
Batu Tara | 25 May-31 May 2011 | Continuing ActivityCite this Report
Batu Tara Komba Island	Based on analyses of satellite imagery, the Darwin VAAC reported that during 24-27 May ash plumes from Batu Tara rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted less than 40 km W, NW, and N. Source: Darwin Volcanic Ash Advisory Centre (VAAC)
Karymsky | 25 May-31 May 2011 | Continuing ActivityCite this Report
Karymsky Eastern Kamchatka (Russia)	KVERT reported moderate seismic activity at Karymsky during 20-27 May. Possible ash plumes rose to an altitude of 6.5 km (21,300 ft) a.s.l. on 21 May and to an altitude of 3.5 km (11,500 ft) a.s.l. on the other days. Satellite imagery showed a thermal anomaly during 19-20, 22, and 24 May, and ash plumes that drifted 38 km SW on 22 May. The Aviation Color Code remained at Orange. Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Kilauea | 25 May-31 May 2011 | Continuing ActivityCite this Report
Kilauea Hawaiian Islands (USA)	HVO reported that two lava lakes at Kilauea were active during 25-31 May. The level of the summit lava lake remained mostly stable deep in the vent inset within the E wall of Halema'uma'u Crater. An increase in the lake level covered the vent on the south side wall during 25-28 May. On other days lava from the vent cascaded down into the lake. A gas plume from the vent drifted SW. The (preliminary) sulfur dioxide emission rate from all east rift zone sources was 700 tonnes/day on 26 May; the emission rates were slowly increasing. Lava from a vent near the W edge of the perched lava lake in the center of Pu'u 'O'o crater floor continued to fill the lake. The lake level fluctuated and occasionally overflowed the edges or flowed through rim breaches, sending lava onto the Pu'u 'O'o crater floor. The rim of the perched lava lake was elevated 10 m higher than the surrounding crater floor, which was 52 m below the E crater rim on 11 May. During 27-29 May lava from a vent at the base of the SW wall produced lava flows that slowly began filling the gap between the crater wall and the perched lake wall. Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Kizimen | 25 May-31 May 2011 | Continuing ActivityCite this Report
Kizimen Eastern Kamchatka (Russia)	KVERT reported that during 20-27 May seismicity from Kizimen was above background levels. Strong tremor was detected on 12 May; tremor amplitude gradually increased from 18 May to 24 May. Satellite images showed a large bright thermal anomaly daily on the volcano during 21-24 and 26 May. The Aviation Color Code remained at Orange. Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Poas | 25 May-31 May 2011 | Continuing ActivityCite this Report
Poas Costa Rica	According to a news article, a team of geologists and volcanologists from the Universidad de Costa Rica (UCR) visited Poás on 25 May and observed 18 phreatic eruptions from Laguna Caliente (the summit lake) in a three-hour period. Source: Inside Costa Rica
Popocatepetl | 25 May-31 May 2011 | Continuing ActivityCite this Report
Popocatepetl Mexico	CENAPRED reported that on 30 May an ash plume from Popocatépetl rose 800 m above the crater and drifted E. Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
Sheveluch | 25 May-31 May 2011 | Continuing ActivityCite this Report
Sheveluch Central Kamchatka (Russia)	KVERT reported that during 20-27 May seismic activity at Shiveluch did not exceed background levels. Strong gas-and-steam activity was observed on 21 May; cloud cover prevented ground-based observations on the other days. Satellite imagery showed ash plumes drifting 58 km SW on 20 May and a thermal anomaly over the lava dome during 19-21 and 24 May. The Aviation Color Code remained at Orange. Based on information from KEMSD, the Tokyo VAAC reported that during 30-31 May eruptions produced plumes that rose to altitudes of 7.6-8.2 km (25,000-27,000 ft) a.s.l. and drifted S. According to news articles, ash plumes caused authorities to reroute a number of international flights in the region. Sources: BNO News, Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)
Taal | 25 May-31 May 2011 | Continuing ActivityCite this Report
Taal Luzon (Philippines)	PHIVOLCS reported that field measurements conducted on 24 May at the E sector inside Taal's Main Crater Lake showed that the water temperature slightly increased from 32.5 to 32.8 degrees Celsius, the pH value became more slightly acidic decreasing from 2.83 to 2.67, and the water level increased by 4 cm. During 25-29 May, between 6 and 10 daily volcanic earthquakes were detected by the seismic network. Some of the earthquakes were felt by nearby residents on the SE part of the island. During 29-30 May, 115 earthquakes were recorded. Twelve of these events were felt at Intensity I-IV by residents of Pira-piraso, Alas-as, and Calauit located in the NE, SW, and SE sectors of Volcano Island, respectively. During 30-31 May there were 31 earthquakes noted. The Alert Level remained at 2 (on a scale of 0-5). Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
Tungurahua | 25 May-31 May 2011 | Continuing ActivityCite this Report
Tungurahua Ecuador	The IG reported that during 24-26 May explosions from Tungurahua were detected by the seismic network. On 24 May an ash plume rose to an altitude of 7 km (23,000 ft) a.s.l. Ashfall was reported in areas SW and W. The next day an ash plume drifted W. On 26 May ash plumes were not observed due to cloud cover but ashfall was reported to the SW; cloud cover prevented observations during 27-29 May. Muddy water was observed in multiple drainages during 26-30 May. Lahars on 27 May caused the highway to Baños to close. The highway remained closed during the next two days due to lahar risk. Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)
Ulawun | 25 May-31 May 2011 | Continuing ActivityCite this Report
Ulawun New Britain (Papua New Guinea)	RVO reported that during 23-27 May gray ash plumes rose above Ulawun's summit crater. Fine ash fell in Ubili and Ulamona on the NW flank on 26 May. Source: Rabaul Volcano Observatory (RVO)

Weekly Reports Archive

Since the Weekly Volcanic Activity Report began in November 2000, there have been 19,386 individual reports over 1,186 weeks (average of 16 per week) on 331 different volcanoes.

Use the dropdowns to choose the year and week for archived Weekly Reports.

 News Feeds and Google Placemarks

 Criteria & Disclaimers

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.

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.

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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)