All times are local unless otherwise stated.

Asosan | 18 May-24 May 2011 | New Activity / Unrest Cite this Report
Asosan Kyushu (Japan)	Based on notices from JMA, the Tokyo VAAC reported that during 18-22 May ash plumes from Aso rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted N, NE, and SE. A pilot noted on 18 May that an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. Source: Tokyo Volcanic Ash Advisory Center (VAAC)
Dieng Volcanic Complex | 18 May-24 May 2011 | New Activity / Unrest Cite this Report
Dieng Volcanic Complex Central Java	CVGHM reported that during 18-22 May seismicity at Dieng Volcanic Complex increased. On 22 May diffuse white plumes rose 20 m from the Timbang cone; plumes from the cone had not been previously observed. The next day carbon dioxide gas emissions increased. CVGHM raised the Alert Level to 2 (on a scale of 1-4). Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Grimsvotn | 18 May-24 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, an eruption from the subglacial Grímsvötn volcano began on 21 May following about an hour of tremor. A GPS-station on the rim of the Grímsvötn caldera had revealed continuous inflation and expansion of few centimeters per year since the 2004 eruption, interpreted as inflow of magma to a shallow chamber. Other precursors over the previous few months were increased seismicity, including some bursts of tremor, and increased geothermal activity. The eruption began at 1630 on 21 May, and at 2000 the eruption plume rose to an altitude over 20 km (65,000 ft) a.s.l. The plume altitude fell to 15 km (49,200 ft) a.s.l. during the night but occasionally still rose to 20 km (65,000 ft) a.s.l. Ash from the lower part of the eruption plume drifted S and at higher altitudes drifted E. A few hours after the onset of the eruption ashfall began over areas S of the Vatnajökull ice cap, more than 50 km from the eruption site. Earthquake locations and limited observations during an initial overflight suggested that the eruption site was in the SW part of the caldera, where the 2004 eruption was located. According to news articles, the road in Skeidarársandur, S of Vatnajökull and part of the ring road around Iceland, closed and remained closed through 24 May. During the morning of 22 May the plume rose to an altitude of 10-15 km (32,800-49,200 ft) a.s.l. The color of the plume was brown-to-grayish and sometimes black close to the source. Most of the plume drifted S, but lower parts traveled SW. Tephra fall was concentrated to the S and to a lesser extent N and E. In the afternoon lightning strikes ranged from 60-70 per hour (up to 300 during one hour) and were most frequent in the ash plume to the S. News outlets noted that the Keflavík airport closed. Ashfall was reported from the Reykjavík area in the SW to Tröllaskagi Peninsula in the N. An article also stated that, according to a geophysicist, the eruption was the largest for Grímsvötn in 100 years, was similar to the eruption of 1873, and was larger than the Eyjafjallajökull eruption of 2010. During 22-23 May the ash plume rose to altitudes of 5-10 km (16,400-32,800 ft) a.s.l. and drifted S at lower altitudes and W at altitudes 8 km (26,200 ft) a.s.l. and higher. Ashfall was detected in several areas throughout Iceland except in some areas to the NW. On 24 May the ash plume was estimated to be mostly below 5 km (16,400 ft) a.s.l. because meteorological clouds over the glacier were at 5-7 km (16,400-23,000 ft) a.s.l. and the plume only briefly rose above the cloud deck. Satellite images showed the plume extending over 800 km from the eruption site towards the S and SE. News articles reported that dozens of carriers rerouted or cancelled flights in Norway, Denmark, and Scotland. Sources: Associated Press, The Local (Sweden), Institute of Earth Sciences, Icelandic Meteorological Office (IMO), Iceland Review
Telica | 18 May-24 May 2011 | New Activity / Unrest Cite this Report
Telica Sierra de los Marrabios	INETER reported that during April seismicity at Telica increased, with earthquake magnitudes ranging up to 3.3 and some explosions detected. On 14 May at approximately 2310 a series of explosions were detected by the seismic network and were accompanied by ash and gas emissions. Tephra fall was reported in La Quemada, 4 km N. During the previous few days residents in nearby communities observed reddish colored gas plumes, and those living on the flanks felt earthquakes. On 16 May the seismic network registered three explosions that were accompanied by gas-and-tephra emissions. One plume rose 1.2 km above the crater. Nearby communities to the SE, including Cristo Rey, Las Colinas, and La Quemada, were affected by the emissions. During 17-18 May another series of small explosions was detected. A gas-and-ash plume rose 600 m above the crater. On 18 May an explosion that lasted 6 minutes produced an ash plume that rose 2.6 km above the crater. Fifteen explosions during 18-19 May were accompanied by gas-and-ash plumes that rose 500-800 m high. Women and children living on the flanks were evacuated. Explosions continued to be detected during 19-20 May with gas-and-ash plumes again rising 500-800 m above the crater. Residents on the N flank in the community of El Ñajo reported that new fumaroles had opened, prompting authorizes to plan for monitoring all wells within a 5-km-radius of Telica. During 20-21 May activity decreased. An observer reported four strong explosions and gas-and-tephra plumes that rose 500-700 m high. Source: Instituto Nicaragüense de Estudios Territoriales (INETER)
Tungurahua | 18 May-24 May 2011 | New Activity / Unrest Cite this Report
Tungurahua Ecuador	IG reported that on 17 May new fumaroles on Tungurahua's W flank, about 1 km below the crater, were observed from the Tungurahua Observatory (OVT) in Guadalupe (11 km N). Explosions during 17-23 May produced gas-and-steam plumes that rose to altitudes of 6-9 km (19,700-29,500 ft) a.s.l and mostly drifted SW, W, and NW. Ashfall was reported on most days in areas within 8 km SW, W, NW, N, and NNE, but reached as far as Guadalupe (11 km N), Ambato (31 km NW), and Penipe (15 km SW). On 17 May incandescence emanated from the crater. Blocks were also ejected from the crater, and rolled down the flanks, on 17, 19, and 21 May. Sounds resembling "cannon shots" were occasionally reported. Large windows vibrated on 21 May. Ash-and-gas plumes rose from the crater on 24 May and likely drifted W. Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)
Ulawun | 18 May-24 May 2011 | New Activity / Unrest Cite this Report
Ulawun New Britain (Papua New Guinea)	RVO reported that during 19-22 May gray-to-brown ash plumes rose above Ulawun and fine ash fell on the NW and W flanks. Weak, fluctuating incandescence was observed on 22 May. Source: Rabaul Volcano Observatory (RVO)

Aira | 18 May-24 May 2011 | Continuing ActivityCite this Report
Aira Kyushu (Japan)	Based on information from JMA, the Tokyo VAAC reported that during 18-22 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. Plumes drifted in multiple directions. On 21 May, a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted N. Source: Tokyo Volcanic Ash Advisory Center (VAAC)
Bagana | 18 May-24 May 2011 | Continuing ActivityCite this Report
Bagana Bougainville (Papua New Guinea)	Based on analyses of satellite imagery, the Darwin VAAC reported that on 21 May an ash plume from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 65 km NW. Source: Darwin Volcanic Ash Advisory Centre (VAAC)
Batu Tara | 18 May-24 May 2011 | Continuing ActivityCite this Report
Batu Tara Komba Island	Based on analyses of satellite imagery, the Darwin VAAC reported that during 17 and 19-22 May ash plumes from Batu Tara rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted 75-110 km W, NW, and N. Source: Darwin Volcanic Ash Advisory Centre (VAAC)
Chaiten | 18 May-24 May 2011 | Continuing ActivityCite this Report
Chaiten Southern Chile	SERNAGEOMIN reported that during 2011 seismic activity from Chaitén remained low and that no growth of the lava-dome complex was detected. Visual observations indicated low emissions. The Alert Level was lowered to Green, Level 2, on a three-color scale. Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)
Dukono | 18 May-24 May 2011 | Continuing ActivityCite this Report
Dukono Halmahera	Based on analyses of satellite imagery, the Darwin VAAC reported that on 19 May an ash plume from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 110 km NE. Source: Darwin Volcanic Ash Advisory Centre (VAAC)
Karymsky | 18 May-24 May 2011 | Continuing ActivityCite this Report
Karymsky Eastern Kamchatka (Russia)	KVERT reported moderate seismic activity at Karymsky during 13-20 May. Seismic data indicated that possible ash plumes rose to an altitude of 2.5 km (8,200 ft) a.s.l. A thermal anomaly was detected in satellite imagery during 16-17 and 19 May. The Aviation Color Code remained at Orange. Based on information from KVERT, the Tokyo VAAC reported that on 21 May an eruption produced a plume that rose to an altitude of 6.7 km (22,000 ft) a.s.l. Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)
Kilauea | 18 May-24 May 2011 | Continuing ActivityCite this Report
Kilauea Hawaiian Islands (USA)	HVO reported that two lava lakes at Kilauea were active during 18-24 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. Lava from a vent above the south side cascaded down into the lake. A gas plume from the vent drifted SW and likely deposited very small amounts of ash nearby. At Pu'u 'O'o crater, lava mostly from a vent near the W edge of the perched lava lake in the center of the 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 several meters higher than the surrounding crater floor, which was 52 m below the E crater rim on 11 May. On 20 May a small lobe of lava visible in the web camera appeared on the W edge of the crater floor. The (preliminary) sulfur dioxide emission rate from all east rift zone sources was 800 tonnes/day on 20 May; the emission rates were slowly increasing. Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Kizimen | 18 May-24 May 2011 | Continuing ActivityCite this Report
Kizimen Eastern Kamchatka (Russia)	KVERT reported that during 13-20 May seismicity from Kizimen was above background levels, and indicated that possible ash plumes rose to an altitude of 5.9 km (19,400 ft) a.s.l. and 4.9 km (16,100 ft) a.s.l. on 14 and 17 May, respectively. Satellite images showed a large bright thermal anomaly daily on the volcano and ash plumes that drifted 24 km S and SE during 14-15 May. The Aviation Color Code remained at Orange. Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Popocatepetl | 18 May-24 May 2011 | Continuing ActivityCite this Report
Popocatepetl Mexico	CENAPRED reported that on 19 May steam-and-gas emissions from Popocatépetl occasionally contained small amounts of ash. The Washington VAAC noted that satellite imagery on 22 May showed a rapidly dissipating area of ash about 650 km SW. Sources: Washington Volcanic Ash Advisory Center (VAAC), Centro Nacional de Prevencion de Desastres (CENAPRED)
Sheveluch | 18 May-24 May 2011 | Continuing ActivityCite this Report
Sheveluch Central Kamchatka (Russia)	KVERT reported that during 15-16 May seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 3.4 km (11,200 ft) a.s.l. According to ground-based observations ash plumes rose to an altitude of 6 km (19,700 ft) a.s.l. on 15 May and to 4 km (13,100 ft) a.s.l. on 16 May. Satellite imagery showed ash plumes drifting 58 km SE on 15 May and a thermal anomaly over the lava dome during 15-16 and 19 May. The Aviation Color Code remained at Orange. Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Soufriere Hills | 18 May-24 May 2011 | Continuing ActivityCite this Report
Soufriere Hills Montserrat	MVO reported that during 13-20 May activity at the Soufrière Hills lava dome was at a low level. On 15 May a pyroclastic flow that occurred in the February 2010 collapse scar caused light ashfall in inhabited areas. The Hazard Level remained at 3. Source: Montserrat Volcano Observatory (MVO)

Weekly Reports Archive

Since the Weekly Volcanic Activity Report began in November 2000, there have been 19,996 individual reports over 1,215 weeks (average of 16 per week) on 332 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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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)