Bulusan Volcano shows increased seismic activity, Phivolcs warns of possible eruptions

The Philippine Institute of Volcanology and Seismology (Phivolcs) reported an increase in seismic activity at Bulusan Volcano in Sorsogon.

From April 12 to April 21, 2025, Phivolcs recorded a total of 94 volcanic earthquakes, including 90 weak and shallow volcano-tectonic earthquakes and four low-frequency volcanic earthquakes generated within 20 kilometers deep beneath the Bulusan edifice.

Phivolcs attributed the slight increase in seismic activity to hydrothermal processes that could lead to short-term pressurization of the volcano's edifice.

While degassing remains at a very weak to moderate level, Phivolcs warned about potential steam-driven or phreatic eruptions from the crater and active vents on the summit without prior warning.

Alert Level 0 (Normal) is currently in effect for Bulusan Volcano, but entry into the 1-kilometer radius permanent danger zone around the volcano should be prohibited to avoid sudden volcanic hazards such as rockfall and ballistic projectiles; additionally, pilots are advised to avoid flying close to the summit due to potential ash hazards.