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Mayon alert level lowered from 3 to 2 13 January 2010

Posted by admin in activity reports, Mayon, Philippines.
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The Philippine Institute of Volcanology and Seismology (Phivolcs) has lowered the alert level for Mayon from 3 (‘relatively high unrest’) to 2 (‘moderate unrest’). Mayon bulletin no. 31 for 13 January 2010 gives the details:

Seismic activity: ‘The network continues to record a few low frequency-type volcanic earthquakes associated with degassing of residual magma … The lack of remarkable seismic events, such as harmonic tremors, suggests no active transport of magma to shallow levels’.

Ground deformation: ‘Results of precise leveling surveys (05-10 January) at the northwest and southeast slopes of the volcano showed deflationary trend compared to 27 November – 03 December 2009 survey. The electronic tiltmeter installed at the upper northwest slope of the volcano also indicated deflation. These measurements indicate a return of the volcanic edifice to a deflated state, suggesting that no pressure build-up has taken place and reflect a general static condition of residual magma in the volcanic pipe and beneath the crater’.

Gas measurements: ‘Sulfur Dioxide (SO2) emission rate was measured yesterday at an average of 597 tonnes/day (t/d). Measured SO2 levels have decreased considerably from a high of 2,621 t/d to a low of 597 t/d. The decrease in concentration of SO2 gas emission further indicates that no active magma intrusion is occurring beneath the volcanic edifice’.

Visual observation: ‘Steam emission was most of the time weak to moderate and white in color indicating considerable decrease in energy. Crater glow remained visible to the naked eye at night possibly due to the still-hot residual magma beneath the crater’.

For all our Mayon coverage: Mayon « The Volcanism Blog.

News
Phivolcs lowers Mayon alert level to 2 – GMANews.TV, 13 January 2010
Phivolcs lowers Mayon alert levelPhilippine Star, 13 January 2010
Mayon alert level lowered to 2Philippine Daily Inquirer, 13 January 2010

Information
Global Volcanism Program: Mayon – summary information for Mayon (0703-03=)
Philippine Institute of Volcanology and Seismology – website for Phivolcs

The Volcanism Blog