826 quakes recorded around Pinatubo

MABALACAT CITY, Pampanga, Philippines —  At least 826 “imperceptible” earthquakes have been recorded in the vicinity of Mt. Pinatubo in this city since Jan. 20 even as it remains in “quiscient condition,” according to the Philippine Institute of Volcanology and Seismology.

Phivolcs said the strongest quake, which had  magnitudes of 2.5 to 1.0 and depths of 15 to 28 kilometers, were recorded on Monday.

The earthquakes were generated along a segment of the Sacobia Lineament, a fault that was last active after Mt. Pinatubo erupted in 1991.

“This development serves to remind us once again that several faults occur around the volcano and that these can generate earthquake activity that can be sometimes imperceptible and harmless, but that can also sometimes be damaging,” Phivolcs said.

It cited the magnitude 6.1 quake that hit the southern foot slopes of the volcano on April 22, 2019, which resulted in deaths and caused substantial damage to infrastructure in Central Luzon.

“Although there is currently no threat from the recent earthquake activity, communities and local government units surrounding the volcano have to be reminded to be always prepared for both earthquake and volcanic hazards and to build on the lessons of what they have experienced in the past years,” Phivolcs said.

The agency said it continues to strengthen its monitoring of the volcano with ongoing upgrades of its network and geochemical surveys of the crater lake.

The eruption of Mt. Pinatubo in 1991 is the second-largest volcanic eruption of the century. At least 800 people died and 200,000 were rendered homeless. - Ramon Efren Lazaro, Helen Flores