MANILA, Philippines – The status of the Bulusan Volcano in Sorsogon was raised from Alert Level 0 to Alert Level 1 on Monday, July 6.

The Philippine Institute of Volcanology and Seismology (Phivolcs) announced in a bulletin at 4 pm on Monday that Alert Level 1 means Bulusan is now “in an abnormal condition.”

Why was the alert level raised? Phivolcs observed an increasing number of volcanic earthquakes and swelling of the volcano.

Phivolcs said a total of 53 volcanic earthquakes have been recorded by Bulusan’s monitoring network since Friday, July 3.

These include “43 low-frequency events that are associated with weak and shallow hydrothermal or magmatic gas activity within the edifice.”

Phivolcs also warned that the growing number of earthquakes “could be succeeded by steam-driven or phreatic eruptions at the summit crater or from flank vents on the upper to middle slopes.”

Ground deformation has been observed at Bulusan as well, particularly “short-term inflation” or swelling of the edifice since late February 2020.

“These parameters indicate that volcanic processes are underway beneath the edifice that may be caused by deep-seated degassing or hydrothermal activity or magmatic intrusion,” said Phivolcs.

What should people do? State volcanologists reminded local government units and the public that entry into the 4-kilometer-radius Permanent Danger Zone around Bulusan is “strictly prohibited.”

There should also be vigilance in the Extended Danger Zone “due to the increased possibilities of sudden and hazardous phreatic eruptions.”

Pilots should avoid flying close to the volcano’s summit as well, since ash from an eruption could be hazardous to aircraft.

Ash from a possible eruption may also mix with rainfall, which could trigger lahar, warned Phivolcs. – Rappler.com