Philippines: Mayon Volcano Bulletin 18

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Philippine Institute of Volcanology and Seismology

31 December 2009
8:00 AM

For the past 24 hours, Mayon Volcano's (13.2576 N, 123.6856 E) activity was characterized by extrusion of lava and rolling down of incandescent lava fragments along the Bonga gully. The summit of the volcano was obscured most of the time yesterday due to thick cloud cover. No ash explosion was observed during times of good visibility. Emission of very weak to moderate volume of white steam that drifted towards west- southwest was observed during clear views of the crater.

Seismic monitoring revealed the occurrence of 60 volcanic earthquakes. A total of 267 rock fall events related to the detachment of lava fragments at the volcano's upper slopes was also detected by the seismic network. Sulfur Dioxide (SO2) emission rate measurements yesterday yielded an average value of 1,158 tonnes per day (t/d). The volcano edifice remains inflated as indicated by the electronic tilt meter installed at the northeast sector of the volcano.

The status of Mayon Volcano is maintained at Alert Level 4. PHIVOLCS-DOST reiterates that the Extended Danger Zone (EDZ) from the summit of 8-km on the southern sector of the volcano and 7-km on the northern sector should be free from human activity. Areas just outside of this EDZ should prepare for evacuation in the event hazardous eruptions intensify. Active river channels and those perennially identified as lahar prone in the southern sector should also be avoided especially during bad weather conditions or when there is heavy and prolonged rainfall. In addition, Civil Aviation Authorities must advise pilots to avoid flying close to the volcano's summit as ejected ash and volcanic fragments from sudden explosions may pose hazards to aircrafts. PHIVOLCS-DOST is closely monitoring Mayon Volcano's activity and any new significant development will be immediately posted to all concerned.