The Philippine Institute of Volcanology and Seismology (PHIVOLCS) has raised Bulusan Volcano in the Bicol Region to Alert Level 1 following a series of sustained volcanic earthquakes recorded over the past week.

In its latest report, the agency said a total of 475 weak volcano-tectonic earthquakes have been detected since 15 March.

PHIVOLCS also observed slight surface deformation of the volcano, along with sulfur dioxide emissions reaching 91 tonnes on 17 March, indicating ongoing seismic activity.

Under Alert Level 1, entry into Bulusan’s four-kilometer permanent danger zone is strictly prohibited. Residents within the two-kilometer extended danger zone have also been warned of possible pyroclastic density current emissions.

Communities on the western side of the volcano were advised to remain vigilant for potential ashfall, while those in southwestern valleys were urged to monitor river channels for sediment-laden flows.

Bulusan had previously been downgraded to Alert Level 0 on 6 February after volcanic activity declined, with no signs of a magmatic eruption at the time.

The volcano last erupted in April 2025 through a phreatic or steam-driven event.

Bulusan currently shares Alert Level 1 status with Taal Volcano in Batangas, which recorded sulfur dioxide emissions of 698 tonnes on Saturday, 21 March.