An advisory released by the Philippine Institute of Volcanology and Seismology (PHIVOLCS) on May 20 recorded a total of 442 volcano-tectonic earthquakes at Bulusan Volcano in Sorsogon over the past two days.

The data, provided by the Bulusan Volcano Network (BVN), covered monitoring from 4 p.m. on May 18 until 12 p.m. on May 20.

According to the BVN, 55 of the recorded earthquakes were located less than five kilometers beneath the volcano’s edifice.

“These parameters may indicate slow pressurization of the edifice due to shallow hydrothermal or tectonic processes beneath the volcano that could lead to steam-driven or phreatic eruptions at any of its summit vents,” PHIVOLCS said.

Alert Level 1, or low-level unrest, remains in effect over Bulusan Volcano.

PHIVOLCS warned the public of increased volcanic activity in the area and advised local government units to prohibit entry into hazardous zones.

“The public is reminded that Alert Level 1 (low-level unrest) prevails over Bulusan Volcano, and increased seismicity raises the chances of phreatic eruptions from any of its summit vents,” the agency said.

“Local government units are advised to strictly prohibit entry into the four-kilometer-radius Permanent Danger Zone (PDZ) and exercise vigilance within the two-kilometer Extended Danger Zone (EDZ),” it added.

DOST-PHIVOLCS said it continues to closely monitor Bulusan Volcano and will provide updates on any significant developments in the coming days.