Catching up: Mayon, Redoubt, Poás, Saudi Arabia… 31 December 2009Posted by admin in activity reports, Alaska, Costa Rica, Mayon, Philippines, Poás, Redoubt.
Tags: Mayon, Poás, Redoubt, Saudi Arabia, volcanic activity reports
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!