The Philippine Institute of Volcanology and Seismology (Phivolcs) raised the alert level of Bulusan Volcano in Sorsogon from 0 to 1 after recording 475 volcanic earthquakes since March 15. The activity signals a return to low-level unrest that could lead to phreatic or steam-driven eruptions.
On March 22, 2026, the Philippine Institute of Volcanology and Seismology (Phivolcs) raised Bulusan Volcano's alert level in Sorsogon province from 0 to 1, noting it had entered a period of low-level unrest. The agency reported 475 volcanic earthquakes since March 15, mostly weak volcano-tectonic events linked to rock fracturing at shallow depths under the edifice. Phivolcs stated, 'Most of these were weak volcano-tectonic earthquakes that are associated with rock fracturing at shallow depths beneath the volcano edifice.' Such swarms preceded phreatic eruptions in June 2022 and April 2025. Inflation was observed on the western flank since late January and the southeastern flank since early March. The agency explained, '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.' Authorities advised against entering the 4-kilometer permanent danger zone due to risks like pyroclastic density currents, ballistic projectiles, rockfall, avalanches, and ashfall. Bulusan had been at Alert Level 0 since February 6. Alert levels range from 0 (normal) to 5 (hazardous eruption in progress). Taal Volcano remains at Alert Level 1 since July 11, 2022; Mayon was raised to 3 on January 6, 2026; Kanlaon was lowered to 2 on July 29, 2025.
