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Christmas Day eruption at Poás captured on video 6 January 2010

Posted by admin in Costa Rica, Poás.
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You may recall our report of a phreatomagmatic display that Poás volcano in Costa Rica put on to celebrate Christmas Day: well, you can now see a video of the event – ‘Central Georgia couple captures video of erupting volcano’ (also at YouTube).

There is also an interview with tourist Tom Wellman, who made the video. Strange remark 1: ‘this type of volcano doesn’t put out liquid lava. Instead it puts out a dry lava with steam’. Strange remark 2: ‘Tom says that this is the first time in the history of Costa Rica that anyone has recorded video of an erupting volcano’. Not really, try this.

Costa Rican newspaper La Nación has some nice still pictures of the Poás eruption, taken by Kristina Kremer.

UPDATE 11 February 2010. Tom Wellman has provided some clarification regarding his video: please see his comment below.

[Hat tip: Damon Hynes via Eruptions.]

The Volcanism Blog

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Catching up: Mayon, Redoubt, Poás, Saudi Arabia… 31 December 2009

Posted by admin in activity reports, Alaska, Costa Rica, Mayon, Philippines, Poás, Redoubt.
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The Volcanism Blog Christmas Break lasted a little longer than intended, as round here the internet celebrated the holiday season by breaking down and we’ve only just got it back. Here’s a summary of what’s been going on in the meantime.

Mayon has so far stopped short of the big explosive eruption that everyone has been expecting (although the full moon might do it). Some 50,000 people have spent Christmas as evacuees in temporary shelters, and it does not look as if they will be returning to their homes any time soon. Meanwhile the authorities are losing patience with people who refuse to quit the danger zone: power and water supplies to evacuated areas are to be cut off, and the Philippine Commission on Human Rights has okayed ‘forcible evacuation’ measures. The latest Phivolcs bulletin (no. 18, 31 December 2009) reports continuing ‘extrusion of lava and rolling down of incandescent lava fragments’. Poor visibility has hampered observations of the volcano, but no ash explosions have been observed during clear periods. The last significant explosion (to 9,000 feet/2,740 metres) was reported by Tokyo VAAC at 00:17 UTC on 30 December. The alert status for Mayon remains at the second-highest level of 4; the level of activity has declined somewhat over the last few days, but Phivolcs warns that the threat remains.

In Alaska, Redoubt stirred for the first time in five months or so, altering its usual seismic behaviour to produce a series of small repetitive earthquakes near its summit. The Alaska Volcano Observatory raised the alert level for Redoubt to Yellow/Advisory on 28 December 2009. The latest AVO bulletin (30 December 2009, 21:46 UTC) reports that the earthquake activity has declined markedly.

Poás in Costa Rica revealed itself to have a great sense of occasion, putting on a fine display of phreatic activity on Christmas morning. A mixture of sediments and water from the crater lake and volcanic blocks was ejected to a height of more than 500 metres at 09:50 on Christmas Day, startling visiting parties of festive tourists.

Remember the earthquakes in the Al-Ais region of Saudi Arabia earlier this year? The last tremors were reported in June. It seems that there were some more earthquakes on 18 December, causing alarm among local residents who have only recently returned to their homes after being evacuated in May and June. The Saudi Geological Service has said that the tremors are normal for this volcanic region of the country, no eruption is imminent, and that there is no need for new evacuations.

The Global Volcanism Program has published two weekly volcanic activity reports over the holiday period, one covering 16-22 December 2009 and one for 23-29 December 2009. Full posts for both of these will be published here next week.

Happy New Year!

The Volcanism Blog

Phreatic eruption at Poás, Costa Rica 21 September 2009

Posted by admin in activity reports, Costa Rica, Poás.
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Poás volcano produced a phreatic eruption on Friday morning, 18 September, reports Costa Rican newspaper La Nación. The eruption projected water and sediment to a height of 300 metres above the surface of the crater lake. It is the northern of the volcano’s two summmit crater lakes, Lago Caliente, which is the site of frequent phreatic eruptions; the most recent, a smaller event, was in January this year.

The report also mentions that scientists visiting the summit of Poás have found burning sulphur on the north wall of the crater lake, the first time this phenomenon has been seen since 1994. Recent high temperatures and low rainfall have reduced the water volume in the highly acidic lake, and degassing from the crater has intensified with the gas plume – ‘bright yellow’ in certain areas – reaching 400 metres in height when measured on 16 September. The sulphurous plume may present a hazard for visitors to the volcano, which is one of Costa Rica’s most popular tourist attractions.

News
Volcán Poás hizo erupción de agua y sedimentosLa Nación, 20 September 2009

Information
Global Volcanism Program: Poás – information about Poás (1405-04=)
Observatorio Vulcanológico y Sismológico de Costa Rica – Volcanological and Seismological observatory of Costa Rica (OVSICORI)
Volcán Poás – profile of Poás volcano from OVSICORI

The Volcanism Blog

Small phreatic eruption at Poás, Costa Rica 16 January 2009

Posted by admin in activity reports, Costa Rica, eruptions, Poás.
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A magnitude 6.1 earthquake took place at 19:21 UTC (13:21 local time) on 8 January 2009 near La Cinchona, Costa Rica, some 6km east of Poás volcano. Poás is a highly active stratovolcano with a recent history of frequent phreatic and phreatomagmatic eruptions. The close proximity of the 8 January earthquake to the volcano has led to concerns that the quake, which produced rockfalls within the crater, could have disturbed the volcano, possibly provoking some kind of eruptive activity.

Ovsicori reports (see source below) that on 12 January 2009 there was a small phreatic eruption at Poás volcano:

The event can be described as a small phreatic eruption with dimensions of 50m diameter and 15m height which occurred in the centre of the lake in the active crater … This can be interpreted as a small eruption of a bubble of gas which was released suddenly from the fractured hydrothermal system.

The implication is that the hydrothermal system, described by Ovsicori as ‘already fractured and shallow’ was disrupted by the earthquake.

A report in Spanish on the 8 January 2009 earthquakes from the Observatorio Vulcanológico y Sismológico de Costa Rica (Ovsicori) is available in PDF at this link. The Ovsicori report on the Poás activity of 12 January 2009 quoted above can be found, also as a PDF, here.

News
Thirteen dead in Costa Rica quake – BBC News, 10 January 2009
Bodies found as quake toll rises – Press Association, 11 January 2009
Death toll in Costa Rica quake rises to 20 – Associated Press, 14 January 2009
Thousands on alert for aftershocks – Inside Costa Rica, 14 January 2009
Preocupados costarricenses por erupciones en el volcán Poás – Prensa Latina, 14 January 2009
Experts say Poás activity normal – Inside Costa Rica, 15 January 2009

Information
Global Volcanism Program: Poás – information about Poás (1405-04=)
Observatorio Vulcanológico y Sismológico de Costa Rica – Volcanological and Seismological observatory of Costa Rica (Ovsicori)
Volcán Poás – profile of Poás volcano from Ovsicori

The Volcanism Blog