Metro Manila (CNN Philippines, January 3) — State seismologists on Tuesday logged an “increase seismic activity” at Bulusan volcano in Sorsogon.
In its advisory, the Philippine Institute of Volcanology and Seismology (Phivolcs) said this may indicate that hydrothermal processes may be occurring beneath the volcano and may lead to steam-driven eruptions at any of the summit vents.
116 earthquakes have been recorded at Bulusan volcano since 9 p.m., Dec. 29, Phivolcs added.
Of these, Phivolcs said 110 were volcano-tectonic earthquakes associated with rock fracturing beneath the southern flanks while six were low frequency volcanic earthquakes related with movement of volcanic fluids.
State seismologists added that inflation or swelling of the southwestern and southeastern slopes of the volcano have also been recorded since February 2023.
Meanwhile, volcanic degassing from the crater and its active vents has been \”very weak to moderate\” when the volcano summit has been visible.
Following the recent development, Phivolcs reminded local government units and the public that entry into the 4-kilometer (km) radius permanent danger zone of the volcano is prohibited while vigilance in the 2-km extended danger zone must be exercised.
It urged civil aviation authorities to advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can damage aircraft.
Residents within valleys along rivers or streams near the volcano were also asked to remain vigilant against sediment-laden stream flows and lahars.
Bulusan volcano was placed under Alert Level 1 in October after a sustained series of volcanic quakes were recorded on the same month.
