Bulusan Volcano in Sorsogon now under normal status – Phivolcs

Mount Bulusan in Sorsogon (File photo)

MANILA, Philippines — Bulusan Volcano in Sorsogon is now under normal condition, according to state volcanologists. 

The Philippine Institute of Volcanology and Seismology (Phivolcs) on Tuesday said it lowered the alert status of Bulusan Volcano from Alert Level 1 (low level of unrest) to Alert Level 0 (normal).

“Bulusan Volcano has returned to normalcy following a general decline in monitoring parameters,” said Phivolcs in its latest advisory.

“This means that monitoring parameters have returned to baseline or background levels and no magmatic eruption is foreseen in the immediate future,” it added.

Phivolcs said the volcanic earthquakes have declined to baseline levels, or 0-5 tremors a day, since the third week of August.  

Phivolcs added that the decline of volcanic earthquakes may be due to the occurrence of the magnitude 6.6 earthquake in Masbate last 2020, which caused significant damage and injuries.

“The decline and characteristics of VT (volcanic-tectonic) earthquake activity indicate that rock-fracturing processes beneath the volcano may have been influenced by diminishing tectonic stresses related to the 18 August 2020 Mw (moment magnitude) 6.6 earthquake along the nearby Masbate segment of the Philippine Fault Zone,” it explained.

Also, Phivolcs said that the sulfur dioxide or SO2 emission from the volcano’s summit vents has been low at an average of 76 tonnes per day since Alert Level 1 was raised on October 25, 2023. 

Degassing activity from Bulusan’s active summit vents has also remained at “background levels,” Phivolcs said and has produced “only very weak to moderate plumes” since September 2023.

Mt. Bulusan is only about 70 kilometers away from Mayon Volcano, which is still under Alert Level 1.