Mt. Bulusan in October 2023.
LEGAZPI CITY — An increase in the number of earthquakes at Mount Bulusan in Sorsogon province was reported by the Philippine Institute of Volcanology and Seismology (Phivolcs) on Tuesday, Jan. 2.
In an 8 p.m. advisory, Phivolcs said the Bulusan Volcano Network recorded 116 earthquakes since 9 p.m. of Dec. 29, 2023.
Phivolcs said 110 were volcano-tectonic earthquakes associated with rock fracturing beneath the southern flanks at depths of two to six kilometers, and the other six were low-frequency tremors associated with the movement of volcanic fluids.
“[The] increased seismic activity and pressurization of the volcano edifice may indicate that hydrothermal processes may be occurring beneath the volcano and may lead to steam-driven eruptions at any of the summit vents,” Phivolcs said in the advisory.
Alert Level 1 (low-level of unrest) was raised over Mount Bulusan on Oct. 25 last year due to the increased volcanic activity.
The agency reminded the public to avoid entering the 4-kilometer radius permanent danger zone due to the increased chances of steam-driven or phreatic eruptions.
People living within valleys and along river or stream channels were also advised to be vigilant against sediment-laden stream flows and lahar in case of heavy and prolonged rainfall.
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