(Eagle News) — The Philippine Institute of Volcanology and Seismology has raised the alert level 1 for Mt. Pinatubo.
In making the move, PHIVOLCS noted the “persistence of seismic activity.”
For instance, since January 20, 2021, it said the Pinatubo Volcano Network (PVN) has detected 1,722 “imperceptible earthquakes” beneath the Pinatubo edifice.
It said the first cluster on Jan. 20-26 occurred along the Sacobia Lineament at depths of 15-28 kilometers and ranged between ML1.0 and ML2.5 in magnitudes.
“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,” PHIVOLCS said.
All earthquakes, it added, were “associated with rock-fracturing processes.”
PHIVOLCS said also monitored at the volcano were a total carbon dioxide flux of 378 tons/day at the Pinatubo Crater lake in February 2021, which it said was “still within the background range of 1,000 tons/day recorded in the past decade.”
“There were also slight increases in the temperatures of monitored gas vents “but other characteristics such as acidity (pH) remain unchanged,” it said.
With the raising of the alert level, PHIVOLCS reminded the public that “entry into the Pinatubo Crater area must be conducted with extreme caution and should be 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,” PHIVOLCS said.
“(Department of Science and Technology)-PHIVOLCS is closely monitoring the volcano’s condition and any new development will be relayed to all concerned,” it added.
