MANILA, July 6 (Xinhua) -- The Philippine Institute of Volcanology and Seismology (Phivolcs) on Monday raised the alert level for Bulusan volcano to 1, saying the volcano located in the southeast of Manila "is currently in an abnormal condition."
In a bulletin, the institute said it recorded a total of 53 volcanic earthquakes since July 3, including 43 "low-frequency events that are associated with weak and shallow hydrothermal or magmatic gas activity within the edifice."
"The increased seismicity could be succeeded by steam-driven or phreatic eruptions at the summit crater or from flank vents on the upper to middle slopes, despite the absence of visible degassing or steaming from the active vent this year," the institute added.
The institute further said that "ground deformation data from continuous global position system (GPS) measurements also indicate short-term inflation of the edifice since late February 2020."
"These parameters indicate that volcanic processes are underway beneath the edifice that may be caused by deep-seated degassing or hydrothermal activity or magmatic intrusion," the institute said.
Phivolcs advised the villagers to stay away from the 4-km radius permanent danger zone (PDZ).
The institute also urged the civil aviation authorities to advise pilots to avoid flying close to the volcano's summit as ash from any sudden phreatic eruption can be hazardous to aircraft.
Bulusan volcano, situated in the province of Sorsogon in the Bicol region, is one of the active volcanoes in the Philippines. The volcano last erupted in January 2018 when it spewed ash about 2.5 km high into the sky above the volcano's crater.
