By Brian Jules Campued
A total of 91 volcano-tectonic earthquakes were detected at Bulusan Volcano by the Philippine Institute of Volcanology and Seismology (Phivolcs) early Tuesday morning.
In an advisory issued at 1:30 a.m., Phivolcs said that the earthquakes were associated with rock fracturing at two to four kilometers (kms) in depth beneath the southwestern flanks of Mt. Bulusan.
“The southwestern as well as southeastern flanks of Bulusan Volcano have been inflated since February 2023 based on ground deformation data from continuous GPS and electronic tilt monitoring,” Phivolcs added.
On the other hand, weak to moderate degassing activity, as well as active vents were observed and were visible from the summit crater.
The agency explained that 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.”
Bulusan Volcano remains under Alert Level 1, exhibiting low-level unrest with increased chances of steam-driven or phreatic eruptions, according to Phivolcs.
Entry into the 4-km permanent danger zone is still prohibited while vigilance must be exercised in the 2-km extended danger zone on the southeast sector.
State seismologists also urged aviation authorities to advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption may endanger the aircraft.
“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 occurring simultaneously with phreatic eruption.” said Phivolcs.
This is the second this month that the agency has observed an increase in seismic activity in Bulusan, the first being on Jan. 11 when a total of 71 volcanic-tectonic earthquakes were detected. – avds
