Phivolcs detects increased seismic activity in Mt. Bulusan

Mt. Bulusan in October 2023.

LEGAZPI CITY — The Philippine Institute of Volcanology and Seismology (Phivolcs) recorded on Tuesday, Jan. 2, an increase in the number of earthquakes in Mount Bulusan in Sorsogon province.

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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