Mt. Bulusan (File photo)
MANILA – An increase in Bulusan Volcano's seismic activity was observed on Thursday, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
Seventy-one volcanic tectonic earthquakes associated with rock fracturing were recorded since 5 a.m.
The magnitudes of the quakes ranged from 0.3 to 2.2, and were 1 to 6 kilometers (km) deep.
"Before this increase, we recorded an average of [up to] five earthquakes a day in Bulusan," Phivolcs Director Teresito Bacolcol told the Philippine News Agency.
Phivolcs also reported degassing from the summit crater, adding that the active vents generated weak to moderate plumes.
"The seismic parameters indicate shallow hydrothermal activity is underway and may lead to steam-driven or phreatic eruption," it said.
Bulusan Volcano is still under Alert Level 1, which means low-level unrest with increased chances of steam-driven or phreatic eruptions.
The public and local government units are reminded that entry into the 4-km radius permanent danger zone is prohibited.
Phivolcs also remind them to be vigilant in the 2-km extended danger zone on the southeast sector, as sudden and hazardous phreatic eruptions are possible.
Aviation authorities, meanwhile, must advise pilots to avoid flying close to the volcano's summit, as ash from sudden eruption could be hazardous to aircraft.
Should phreatic eruption occur, those living within the valleys and along river or stream are advised to be vigilant against sediment-laden stream flows and lahar in case of heavy and prolonged rainfall. (PNA)
