All times are local unless otherwise stated.

Masaya | 23 May-29 May 2001 | New Activity / Unrest Cite this Report

Masaya Nicaragua

The Washington VAAC reported that Masaya may have erupted on 23 May at ~1300. Ground observations from the capital city of Managua, 20 km NW of the volcano, indicated that there was a reduction in visibility to the SE of the city due to volcanic "smoke" and steam. The presence of the ash cloud could not be confirmed on satellite imagery due to thunderstorms in the area. Source: Washington Volcanic Ash Advisory Center (VAAC)

Cleveland | 23 May-29 May 2001 | Continuing ActivityCite this Report
Cleveland Chuginadak Island (USA)	Neither eruptive activity nor thermal anomalies have been observed at Cleveland during the previous 6 weeks. Source: US Geological Survey Alaska Volcano Observatory (AVO)
Etna | 23 May-29 May 2001 | Continuing ActivityCite this Report
Etna Sicily (Italy)	According to the Italy's Volcanoes website, through 25 May at Southeast Crater lava continued to flow from a small cone on its NNE flank and mild Strombolian activity continued at its summit vent. Volcanic activity had been relatively regular since a strong eruptive episode began on 9 May. Source: Italy's Volcanoes
Guagua Pichincha | 23 May-29 May 2001 | Continuing ActivityCite this Report
Guagua Pichincha Ecuador	Based on information from the IG, the Washington VAAC reported that on 25 May at 1110 a steam-and-ash emission from Guagua Pichincha's summit rose up to ~8.5 km a.s.l. The cloud was not visible on satellite imagery. Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Washington Volcanic Ash Advisory Center (VAAC)
Kilauea | 23 May-29 May 2001 | Continuing ActivityCite this Report
Kilauea Hawaiian Islands (USA)	The tilt event that began on 20 May ended the following day and HVO reported that the precursory deflation, remarkably rapid inflation of 10-11 microradians in one hour, and then the slow relaxation of the summit presumably recorded a pulse of magma supplied to the summit reservoir complex. The pulse was then transferred to the Pu`u `O`o area where it is currently stored. Lava continued to flow into the ocean at the SE corner of the lava flow field. On 23 May surface lava flows were visible. On 26 May tremor occurred at low-to-moderate levels beneath Pu`u `O`o, earthquake swarms occurred beneath Kilauea caldera, and background tremor was low. Tiltmeters in the summit area and along the east rift zone indicated no significant deformation. Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Mayon | 23 May-29 May 2001 | Continuing ActivityCite this Report
Mayon Luzon (Philippines)	During the week seismic activity was relatively low at Mayon and was associated with occasional rockfalls that descended to the SE down the Bonga Gully. In addition, moderate steaming occurred, incandescence was occasionally observed at the crater, and SO2 emission (up to 5,700 metric tons/day) was above the baseline value of 500 tons/day. On 28 May at 1036 the seismic network recorded a low-frequency volcanic earthquake that was inferred from seismic data to be associated with an ash puff. The ash puff not visible due to meteorological cloud cover. Alert Level 3 remained in effect, prohibiting entry within the 6-km-radius permanent danger zone. PHIVOLCS warned that residents around the volcano, especially those staying in areas facing the Bonga Gully and the SE sector, should be vigilant and prepared to evacuate at any time. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
Popocatepetl | 23 May-29 May 2001 | Continuing ActivityCite this Report
Popocatepetl Mexico	Small-to-moderate sized exhalations occurred during the week. Based on information from the Mexico City MWO, the Washington VAAC reported that an eruption occurred on 26 May at 1122 that sent a steam-and-ash plume up to ~7 km a.s.l. Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC)
Sheveluch | 23 May-29 May 2001 | Continuing ActivityCite this Report
Sheveluch Central Kamchatka (Russia)	On 22 May at 0209 an explosive eruption produced a mushroom-shaped ash column that rose to a height of more than 10 km a.s.l. (preliminary reports stated ~20 km). The high-pressure system over N Kamchatka caused the plume to remain fairly stationary over the region as it spread out to cover an area of ~50,000 km2. Observations from the town of Klyuchi, 46 km from the volcano, revealed that the new lava dome (first observed on 12 May) and the W part of the old dome were destroyed during the eruption. After the 22 May eruption several small eruptions produced ash-and-gas clouds that rose up to 2 km a.s.l. On 23 May a large thermal anomaly was observed at Shiveluch. In satellite imagery the anomaly consisted of ten pixels ranging in temperature from 30 to 49 °C with two pixels near saturation. The anomaly may have represented a pyroclastic flow that originated from the dome area. Seismic activity remained above background levels. On 24 May the Concern Color Code was reduced from Red to Orange. Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Soufriere Hills | 23 May-29 May 2001 | Continuing ActivityCite this Report
Soufriere Hills Montserrat	MVO reported that during 18-25 May volcanic activity increased in comparison to the previous week. The main increase in activity occurred during 19 to 21 May when many large long-period and hybrid earthquakes were recorded. Low-level convective ash clouds generated during this increase in activity rose less than 2 km a.s.l. Observations confirmed that the main growth area was still concentrated in the S sector of the lava dome. A large volume of new talus had built out above the White River, to the S of the volcano, and on 24 May near-continuous rockfalls and small pyroclastic flows were observed. Sulfur dioxide flux increased, with an average of 700 metric tons per day measured on 21 May, considerably higher than the average flux during previous weeks of 100 to 200 tons per day. Due to the increase in activity the daytime entry zone was closed beginning on 21 May. Source: Montserrat Volcano Observatory (MVO)
Tungurahua | 23 May-29 May 2001 | Continuing ActivityCite this Report
Tungurahua Ecuador	Based on information from the IG, the Washington VAAC reported that on 26 May at 2215 ash from an eruption of Tungurahua was observed at a height of ~7 km a.s.l. drifting to the NE. Extensive cloudiness in the area prohibited ash cloud detection on satellite imagery. Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Washington Volcanic Ash Advisory Center (VAAC)

Weekly Reports Archive

Since the Weekly Volcanic Activity Report began in November 2000, there have been 19,408 individual reports over 1,187 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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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)