LEGAZPI CITY – Mount Bulusan in Sorsogon was rocked by 12 volcanic earthquakes over the last two days, signifying the volcano’s continued restiveness, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
Eduardo Laguerta, Phivolcs resident volcanologist here, said Wednesday the quakes and the swelling of the volcano’s edifice were signs that pressure was building up in the volcano’s vent.
Over the last 48 hours, Phivolcs instruments recorded 8 volcanic quakes overnight until 8 a.m., Tuesday, and another 4 quakes overnight until 8 a.m., Wednesday.
The Philvocs Precise Leveling Surveys and GPS meanwhile indicated very slight inflationary trend at the volcano’s edifice, according to Laguerta.
Alert Level 1 (abnormal) remains hoisted over the volcano.
The public is warned to keep off the 4-kilometer Permanent Danger Zone (PDZ) due to the possibility of a sudden and hazardous steam-driven, or phreatic, eruption.
The Phivolcs bulletin advises pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be dangerous to aircraft.
It also warned residents in valleys and along river channels around the volcano of possible flooding and lahar flows in the event of heavy and prolonged rains.
A recent Phivolcs survey discovered a significant volume of lahar deposit along its slopes that could feed a lahar flow in the event of heavy rainfall.
The Office of Civil Defense (OCD) in Bicol said at least seven steam-driven explosions were recorded on the volcano since June, with ash columns rising as high as 1.5 kilometers that had affected the villages along the slopes of the volcano in the towns of Bulusan, Juban and Irosin.
OCD and health officials here had earlier provided face masks to residents in areas affected by ash fall and attended to some villagers who had complained of respiratory ailments resulting from ash inhalation.