The Philippine Institute of Volcanology and Seismology (Phivolcs) has raised the alert status on Mount Pinatubo, from normal to Level 1 (low-level unrest).
Philvolcs Director Renato Solidum, Jr. said Thursday the increasing number of volcanic earthquakes observed has prompted them to raise Mt. Pinatubo’s alert status.
Phivolcs records show it has recorded 1,722 imperceptible earthquakes since last January 20, 2021 with magnitudes 0.5 to 2.8, beneath the Pinatubo edifice. The daily volcanic quake average in alert level 0 is below five.
Imperceptible earthquakes, Solidum explained, are volcanic seismic activities that are not felt. Phivolcs’ Pinatubo volcano bulletin issued Thursday said all earthquakes recorded are associated with rock-fracturing processes.
“Measurements at Pinatubo Crater lake in February 2021 yielded a total CO2 flux of 378 tonnes/day which is still within the background range of 1,000 tonnes/day recorded in the past decade,” the bulletin added.
The document said slight increases in the temperatures of monitored fumaroles or gas vents were also recorded but other characteristics such as acidity (pH) remain unchanged.
While Mt. Pinatubo is not expected to erupt soon, Solidum said residents must take precautions as this data indicate there is volcanic activity. “Take extra caution when entering the Pinatubo crater, and one should only go there when necessary,” he advised.
Solidum also pointed out that while it may take many years before Mt. Pinatubo could erupt again, the public must not be complacent. Phivolcs continuously monitors its volcanic activity, including other factors like a strong earthquake that could strike near Mt. Pinatubo, as this could affect the volcano.
“We will see whether we need to raise or lower the alert status of the volcano,” he said. He also urged LGUs around Pinatubo to review their disaster risk reduction and management plans.
Solidum likewise assured that as of Thursday, other active volcanoes — Taal, Mayon, and Kanlaon — are still under alert level 1, but advised residents near those volcanoes must not enter their Permanent Danger Zones.
Mt. Pinatubo’s last eruption was on June 15, 1991, and back then it was described as the world’s largest volcanic eruption to happen in the past 100 years. It emitted bursts of gas-charged magma into umbrella ash clouds. Hot flows of gas and ash descended the volcano and lahar swept down the valleys.
For centuries, Pinatubo had been quiet prior to its eruption in 1991. In April that year Solidum said the volcano showed early signs of activity. It erupted less than two months later.