The Philippine Institute of Volcanology and Seismology (Phivolcs) has monitored an increase in volcanic activity at Bulusan Volcano in Sorsogon in the past few days.

“A total of 29 volcanic earthquakes were recorded since 5 a.m. of 6 October 2022 by the Bulusan Volcano Network or BVN. Ground deformation data from continuous GPS measurements and radial tilt indicate a short-term inflation of the general southern edifice of Bulusan Volcano since April 2022,” Phivolcs said in an advisory on Friday, Oct. 7.

Phivolcs said Bulusan Volcano averaged 279 tons per day of sulfur dioxide emission on Sept. 29.

Likewise, weak to moderate emission of white steam-laden plumes was observed at the crater, while very weak emission of white-steam laden plumes was seen at the volcano’s northwest vents.

“The increased seismic activity and short-term ground deformation are likely caused by shallow hydrothermal processes beneath the edifice,” it pointed out.

Phivolcs said that Alert Level 0 or “normal” status is maintained over Bulusan Volcano but is subject to change should the current activity persist.

“Since hydrothermal processes are underway beneath the volcano, there are increased chances of steam-driven or phreatic eruptions from its active vents,” it added.

Phivolcs advised local government units and the public that entry into the four-kilometer radius permanent danger zone is prohibited.

“Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft,” it added.