The Philippine Institute of Volcanology and Seismology (Phivolcs) has observed an increase in volcanic activity of Bulusan Volcano.
In an advisory on Monday night, Phivolcs said 62 volcanic earthquakes were recorded since May 7.
It said these earthquakes are caused by movements or eruptions of magma from the volcano, compared to tectonic quakes which are caused by fault movements.
A steady inflation of the upper slopes of the edifice that began last March 6 was recorded.
“Ground deformation data from continuous GPS measurements indicate a short-term slight inflation since February 2021 while the long-term trend from July 2019 denotes that the edifice is still deflated,” Phivolcs added.
Very weak to weak emission of white steam-laden plumes could be observed, according to Phivolcs.
While Alert Level 0 (normal) is maintained over the Bulusan Volcano, Phivolcs noted that this is subject to change should current activity persist.
“Since hydrothermal processes are underway beneath the volcano, there are increased chances of steam-driven or phreatic eruptions from its active vents,” it said.
Entry into the 4-kilometer radius permanent danger done (PDZ) should be prohibited, Phivolcs reminds the public and local government units.
Pilots must be advised to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft, it added.
Bulusan Volcano has been on Alert Level 0 since October 26, 2020.