(UPDATE) Phivolcs lowers Mayon's alert level to 2


Posted at Jan 13 2010 09:02 AM | Updated as of Jan 13 2010 09:23 PM

MANILA, Philippines - The Philippine Institute of Volcanology and Seismology said on Wednesday said it has lowered the alert level raised around Mayon Volcano from 3 to 2 due to a decline in its overall activity.


"Phivolcs is now lowering the alert status from Alert Level 3 to Alert Level 2. This means a further reduction in the likelihood of hazardous eruption," Phivolcs said in its 7 a.m. bulletin on Wednesday.


The Phivolcs said the volcano's seismic activity has continued to decrease since the alert level was lowered from 4 to 3 late December. Gas measurement has also lowered to an average of 597 tons per day compared to previous measurements of an average of 2,621 tons per day.


It added that no ash ejections were observed since December 29, and the volcano's steam emission "was most of the time weak to moderate and white in color indicating a considerable decrease in energy.”


The Phivolcs bulletin said only 6 volcanic earthquakes were recorded for the past 24 hours. It added that the seismic monitoring network has also been recording a "few low frequency-type volcanic earthquakes associated with degassing of residual magma."


It said that majority of the type of earthquakes recorded for the past 2 weeks were only related to rockfalls and rolling down of lava fragments from the volcano's upper slopes.


"The lack of remarkable seismic events, such as harmonic tremors, suggests no active transport of magma to shallow levels," the Phivolcs said.


The agency added that the electronic tiltmeter installed at the upper northwest slope of the volcano has also showed indications of deflation, indicating a return of the volcanic edifice to a deflated state that suggests 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."


The Phivolcs, however, still cautions people to avoid entering the 6-kilometer radius permanent danger zone and the 7-kilometer extended danger zone on the southeast part of the volcano due to continuing threats from sudden explosions, rockfalls and pyroclastic flows due to sudden collapse of unstable lava deposits.


It said there is still a possibility of resurgence in the volcano's activity, and the alert level may still be raised back to 3. It added that only a noticeable downward trend in the volcano's activity would prompt the lowering of the alert level to 1.