Sorsogon’s Bulusan Volcano raised to Alert Level 1

MANILA, Philippines – The alert level of Sorsogon province’s Bulusan Volcano was raised from 0 to 1 on Sunday, March 22, as the volcano “entered a period of low-level unrest” and chances of phreatic or steam-driven eruptions increased.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said in a bulletin on Sunday that it has recorded 475 volcanic earthquakes at Bulusan since March 15.

“Most of these were weak volcano-tectonic earthquakes that are associated with rock fracturing at shallow depths beneath the volcano edifice,” Phivolcs said.

Swarms of volcanic earthquakes had preceded Bulusan’s phreatic eruptions in June 2022 and April 2025.

State volcanologists added that Bulusan’s western and southeastern flanks have been inflated or swollen since the last week of January and the first week of March, respectively.

“Overall, these parameters could indicate that shallow hydrothermal processes beneath the volcano are underway that could lead to steam-driven or phreatic eruptions at any of its summit vents,” Phivolcs said.

Due to the risk of phreatic eruptions occurring, Phivolcs reminded local government units and the public not to enter the 4-kilometer-radius permanent danger zone surrounding Bulusan. Possible volcanic hazards include “pyroclastic density currents, ballistic projectiles, rockfall, avalanches, and ashfall.”

Prior to Sunday, Bulusan had been under Alert Level 0 since February 6. The alert levels range from 0 (normal) to 5 (hazardous eruption in progress).

Aside from Bulusan, Batangas province’s Taal Volcano is also currently under Alert Level 1, which it has maintained since July 11, 2022. Albay province’s Mayon Volcano was raised to Alert Level 3 just last January 6, while Negros Island’s Kanlaon Volcano was downgraded to Alert Level 2 on July 29, 2025. – Rappler.com