THE Philippine Institute of Volcanology and Seismology yesterday raised Alert Level 1 in Mt. Pinatubo due to persistent seismic activity but added no imminent eruption is expected.
“This means that there is low-level unrest that may be related to tectonic processes beneath the volcano,” the agency said in its bulletin raising the alert level.
The agency said entry into the volcano’s crater area should be done “with extreme caution” or avoided if possible.
“Communities and local government units surrounding Pinatubo are reminded to be always prepared for both earthquake and volcanic hazards and to review, prepare and strengthen their contingency, emergency and other disaster preparedness plans,” the agency added.
Since January 20, PHIVOLCS said it has recorded a total 1,722 “imperceptible earthquakes beneath the Pinatubo edifice.
“The first cluster of earthquakes on 20-26 January 2021 occurred along the Sacobia Lineament at depths of 15-28 kilometers and ranged between ML1.0 and ML2.5 in magnitudes,” PHIVOLCS said.
“This has been succeeded by a more persistent cluster of earthquakes occurring along a north-northwest-south-southeast-trending structure 10 to 35 kilometers beneath the center of the edifice itself, with a few shallower earthquakes occurring on both ends of the cluster.
The earthquakes ranged between ML0.5 and ML2.8 in magnitude; all earthquakes recorded are associated with rock-fracturing processes.
The agency that measurements at Mt. Pinatubo’s crater lake last month yielded a total of carbon dioxide flux of 378 tons per day. The data, it said, was “still within the background range of 1,000 tons per day recorded in the past decade.
“Slight increases in the temperatures of monitored fumaroles or gas vents were recorded but other characteristics such as acidity remain unchanged,” it added.