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Arenal: increased activity causes concern 4 April 2009

Posted by admin in activity reports, Arenal, Costa Rica, volcano monitoring.
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Arenal at night, photographed 7 April 2006 by Scott Robinson (Creative Commons license)

Costa Rica’s Comisión Nacional de Emergencias (CNE) is stepping up monitoring of Arenal volcano following an increase in seismic activity over the last month. The national seismological monitoring network (Red Sismológica Nacional) reports that 45 earthquakes were recorded during March, compared with ‘4 or 5’ in February. Seismologist Guillermo Alvarado is quoted in the Mexican newspaper El Financiero as saying that similar behaviour to that recorded in March preceded significant eruptive activity in 1975, 1993, 2000 and 2001. The CNE will be co-ordinating measures to ensure that tourists visiting Arenal and its surroundings over the Easter holidays are kept to safe areas and informed about potential dangers.

Note the irresponsible headline on the English-language Inside Costa Rica story: ‘Experts predicting major activity from Arenal volcano’. They are doing nothing of the sort: volcanologists and seismologists never predict, they only forecast, and in this case they are not even doing that, they are just drawing attention to a pattern of behaviour that has in the past been associated with eruptive activity and working with the authorities to ensure that warnings are issued and prudent precautions are taken. The Inside Costa Rica story itself contradicts its own headline by reporting that Eliécer Duarte of the Observatorio Vulcanológico y Sismológico de Costa Rica ‘said that the volcano has maintained sustained activity for the last 40 years and that, although there will be new flows and related activities, it does not necessarily mean a precursor to “major” cycles and the basis for the predictions’ — the ‘predictions’ none of the experts are making, because there is no basis for them.

Image: Arenal, photographed 7 April 2006 by Scott Robinson (Creative Commons license). [source]

News
Experts predicting major activity from Arenal volcanoInside Costa Rica, 2 April 2009
Vigilan en Costa Rica al volcán ArenalEl Financiero, 3 April 2009
CNE aumenta vigilancia en ArenalLa Nación, 3 April 2009

Information
Global Volcanism Program: Arenal – summary information for Arenal (1405-033)
Observatorio Vulcanológico y Sismológico de Costa Rica – main page for Ovsicori

The Volcanism Blog

SI/USGS Weekly Volcanic Activity Report, 11 March 2009 – 17 March 2009 19 March 2009

Posted by admin in activity reports, Alaska, Arenal, Asama, Batu Tara, Chaitén, Chile, Colombia, Costa Rica, Ecuador, Fuego, Galeras, Guatemala, Hawaii, Indonesia, Japan, Kamchatka, Karymsky, Kilauea, Koryaksky, Nevado del Huila, Pacaya, Pacific, Papua New Guinea, Peru, Rabaul, Redoubt, Russia, Sakura-jima, Santa María, Shiveluch, Suwanose-jima, Tonga, Tungurahua, Ubinas, United States, Weekly Volcanic Activity Reports.
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SI/USGS Weekly Volcanic Activity Report 11 March 2009 - 17 March 2009

The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 11 March 2009 to 17 March 2009 is now available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

New activity: Ebeko (Paramushir Island), Galeras (Colombia), Hunga Tonga-Hunga Ha’apai (Tonga), Koryaksky (Kamchatka, Russia), Redoubt (Alaska, USA), Semeru (Java, Indonesia).

Ongoing activity: Arenal (Costa Rica), Asama (Japan), Batu Tara (Komba Island, Indonesia), Chaitén (Chile), Fuego (Guatemala), Karymsky (Kamchatka, Russia), Kilauea (Hawaii, USA), Nevado del Huila (Colombia), Pacaya (Guatemala), Rabaul (Papua New Guinea), Sakura-jima (Japan), Santa María (Guatemala), Shiveluch (Kamchatka, Russia), Suwanose-jima (Japan), Tungurahua (Ecuador), Ubinas (Peru).

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SI/USGS Weekly Volcanic Activity Report, 11 February 2009 – 17 February 2009 19 February 2009

Posted by admin in activity reports, Alaska, Arenal, Asama, Caribbean, Colombia, Costa Rica, Dukono, eruptions, Galeras, Guatemala, Hawaii, Indonesia, Japan, Kamchatka, Karymsky, Kilauea, Papua New Guinea, Popocatépetl, Rabaul, Redoubt, Russia, Sakura-jima, Santa María, Shiveluch, Soufrière Hills, Tungurahua, Ubinas, United States, Weekly Volcanic Activity Reports.
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SI/USGS Weekly Volcanic Activity Report 11 February 2009 - 17 February 2009

The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 11 February 2009 to 17 February 2009 is now available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

New activity: Asama (Japan), Ebeko (Kuril Islands, Russia), Galeras (Colombia), Redoubt (Alaska, USA).

Ongoing activity: Arenal (Costa Rica), Dukono (Halmahera, Indonesia), Karymsky (Kamchatka, Russia), Kilauea (Hawaii, USA), Popocatépetl (Mexico), Rabaul (Papua New Guinea), Sakura-jima (Japan), Santa María (Guatemala), Shishaldin (Alaska, USA), Shiveluch (Kamchatka, Russia), Soufrière Hills (Montserrat), Tungurahua (Ecuador), Ubinas (Peru).

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Arenal: recent activity 10 June 2008

Posted by admin in activity reports, Arenal, Costa Rica, volcanoes.
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Arenal volcano in Costa Rica is a youthful and vigorous stratovolcano, almost continually active since its current phase of activity began with a violent and deadly eruption in 1968. To quote the Global Volcanism Program’s Arenal summary, ‘Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank’.

The most recent instance of this type of activity was reported by the Observatorio Vulcanológico y Sismológico de Costa Rica (the inevitable acronym is OVISCORI) on 6 June 2008. A pyroclastic flow was generated on the south-western flank of Arenal when an accumulation of blocky, andesitic lava at the summit, the remnant of a March 2007 lava flow, collapsed. The flow descended some 800m, with pulverized material rising from it to produce a tall plume of gases and dust that provoked alarm in tourists and park officials The park was quickly evacuated and closed, no-one was hurt, and there was no further activity.

Bulletins on this activity (PDF) in both Spanish and English can be accessed from OVISCORI’s ‘Informes de Prensa’ page.

Arenal provides a fascinating case study in the ways human societies interact with and live alongside active volcanoes: its spectacular but largely safe activity attracts thousands of visitors, and it is at the heart of a national park that is one of Costa Rica’s main tourist attractions, while the lake at the foot of the volcano, Lago Arenal, has become the site of a large hydroelectric scheme that provides around 40% of the country’s electricity. Arenal.net, a travel-oriented site, offers a great deal of information about the volcano including maps, photographs and links.

UPDATE: There’s a report on what’s happened at Arenal, with some nice clear discussion of the science behind this kind of activity, over at Erik’s Eruptions blog.

Information
Global Volcanism Program: Arenal – volcano information for Arenal (1405-033)
Observatorio Vulcanológico y Sismológico de Costa Rica – main page for Ovsicori

The Volcanism Blog