MANILA, Philippines – State volcanologists raised Sorsogon province’s Bulusan Volcano from Alert Level 0 to Alert Level 1 on Wednesday, October 25, which means that the volcano is in “a state of low-level unrest.”

The Philippine Institute of Volcanology and Seismology (Phivolcs) said in an advisory on Wednesday afternoon that it has observed “a sustained series of volcanic earthquakes,” totaling 121, since October 14.

“Of these, 37 were volcano-tectonic earthquakes that are associated with rock fracturing processes at depths of 1 to 9 kilometers beneath the northwestern and southeastern slopes of the volcano edifice,” Phivolcs said.

There has also been inflation or swelling of the southern flank of Bulusan since February, and of the northeastern flank since September.

In addition, Phivolcs monitored “a notable increase of volcanic carbon dioxide concentrations” from June to August, and higher temperature since February “in a monitored spring on the southwestern slopes.”

“These parameters indicate that hydrothermal activity driven by deep-seated magma degassing may be occurring beneath the volcano and may lead to steam-driven eruptions at any of its summit vents,” the agency warned.

Phivolcs reminded local government units and the public that entry into the 4-kilometer-radius permanent danger zone surrounding Bulusan should be prohibited.

Before Wednesday’s advisory, Bulusan had been under Alert Level 0, the lowest, since January 18. But there were signs in recent months that it could be raised to Alert Level 1, such as increasing volcanic earthquakes. – Rappler.com