Bulusan Volcano’s monitoring network recorded five (5) volcanic earthquakes during the past 24-hour observation period. Very weak emission of white steam-laden plumes from the lower southeast vent was observed. Sulfur dioxide (SO2) emission was measured at an average of 48 tonnes/day on 20 May 2021. Ground deformation data from real-time electronic tilt monitoring recorded sustained inflation of the upper slopes that began 6 March 2021 consistent with short-term inflation of the edifice measured by continuous GPS monitoring since February 2021. These parameters generally indicate that shallow hydrothermal processes are occurring beneath the edifice.Bulusan Volcano’s monitoring network recorded five (5) volcanic earthquakes during the past 24-hour observation period. Very weak emission of white steam-laden plumes from the lower southeast vent was observed. Sulfur dioxide (SO2) emission was measured at an average of 48 tonnes/day on 20 May 2021. Ground deformation data from real-time electronic tilt monitoring recorded sustained inflation of the upper slopes that began 6 March 2021 consistent with short-term inflation of the edifice measured by continuous GPS monitoring since February 2021. These parameters generally indicate that shallow hydrothermal processes are occurring beneath the edifice.

Alert Level 1 status now prevails over Bulusan Volcano, which means that it is currently in an abnormal condition. Local government units and the public are reminded that entry into the 4-kilometer radius Permanent Danger Zone (PDZ) must be strictly prohibited and that vigilance in the 2-kilometer Extended Danger Zone (EDZ) on the southeast sector must 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 should phreatic eruption occur. DOST-PHIVOLCS is closely monitoring Bulusan Volcano’s condition and any new development will be communicated to all concerned stakeholders.

DOST-PHIVOLCS