Bulusan Volcano showing signs of unrest anew

LEGAZPI CITY, Philippines — Nine months after its alert level was downgraded to zero, the Bulusan Volcano in Sorsogon is showing restiveness again, according to the Philippine Institute of Volcanology and Seismology.

Phivolcs recorded 87 volcanic earthquakes around Bulusan from Oct. 14 until yesterday, or an average of 8.7 quakes per day.

State volcanologists classified 29 of the quakes as volcano-tectonic or associated with rock fracturing processes occurring one to eight kilometers under the southern and western sectors of Bulusan.

As these developed, Phivolcs continued to record a high number of volcanic earthquakes and tremors from Mayon until yesterday.

Phivolcs recorded 69 earthquakes, 67 tremors that lasted an hour and 19 minutes, 43 rockfall events and 727 tons of sulfur dioxide emissions from Mayon in the past 24 hours.

Bobby Tuprio, Phivolcs resident volcanologist based at the Cabid-An Observatory in Sorsogon City, said they are closely monitoring the earthquakes, degassing activities and sulfur dioxide emissions on the summit crater and vents of Bulusan.

“Should these abnormal activities increase in the coming days, we might raise the alert level from zero to one,” Tuprio told The STAR yesterday.

Phivolcs said that degassing on the active summit crater and vents had been weak to moderate in the past week.

Sulfur dioxide emissions last week averaged near background levels at 241 tons per day.

Phivolcs detected an inflation on Bulusan’s southern flank and a notable increase of carbon dioxide concentration in a spring located on the southwestern portion of the volcano.

“The above parameters indicate that hydrothermal activity driven by deep magma degassing may be occurring beneath the volcano and may lead to steam-driven eruptions in any of the summit vents,” Phivolcs said.