This is a notice of an increase in activity of Bulusan Volcano. A total of twenty (20) volcanic earthquakes which includes one (1) tornillo and three (3) low frequency events (LFVQs) were recorded within the last 30 hours by the Bulusan Volcano Network or BVN. Electronic tilt recorded a steady inflation of the upper slopes of the edifice that began on 6 March 2021. Ground deformation data from continuous GPS measurements indicate a short-term slight inflation since February 2021 while the long-term trend from July 2020 denotes that the edifice is still deflated. Only very weak to weak emission of white steam-laden plumes could be observed at the southeast vents presently. The increased seismic activity and short-term ground deformation are likely caused by shallow hydrothermal processes beneath the edifice.

Alert Level 0 (Normal) is maintained over Bulusan Volcano but is subject to change should current activity persist. Since hydrothermal processes are underway beneath the volcano, there are increased chances of steam-driven or phreatic eruptions from its active vents. Local government units and the public are reminded that entry into the 4-kilometer radius Permanent Danger Zone (PDZ) should be prohibited and that vigilance in the Extended Danger Zone (EDZ) should be exercised due to the increased possibilities of sudden and hazardous phreatic eruptions. Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft. Furthermore, people living within valleys and along river/stream channels especially on the southeast, southwest and northwest sector of the edifice should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall. DOST-PHIVOLCS is closely monitoring Bulusan Volcano’s condition and any new development will be communicated to all concerned stakeholders.

DOST-PHIVOLCS