BULUSAN VOLCANO ADVISORY

21 September 2023

02:00 P.M.

A total of twenty-two (22) volcano-tectonic earthquakes were recorded by Bulusan Volcano Network (BVN) since 5:00 AM yesterday, 20 September 2023. The strongest of these were recorded at local magnitudes of ML 0.1 to ML 1.5 and originated between 1 to 5 kilometers beneath the southern sector of Bulusan Volcano. Degassing at the active summit crater and vents have been weak to moderate this week, while volcanic SO2 emission today averaged 100 tonnes/day, well within baseline levels. Ground deformation data from continuous GPS monitoring indicate inflation of the edifice since December 2022, while electronic tilt data indicate a short-term and ongoing inflation of the southeastern flank since February 2023.

Alert Level 0 (Normal) is maintained over Bulusan Volcano but there are increased chances of steam-driven or phreatic eruptions occurring at the crater or summit area. Local government units and the public, however, are reminded that entry into the 4-kilometer radius Permanent Danger Zone (PDZ) particularly near the vents on the south-southeastern slopes, should be avoided due to the possibility of sudden and hazardous steam-driven or phreatic eruption, rockfall and landslide. 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 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 relayed to all concerned.

DOST-PHIVOLCS