Mount Bulusan in Sorsogon rumbles, spews ash; Alert Level 1 raised

Mount Bulusan / Bulusan Volcano in Sorsogon (file photo)

LEGAZPI CITY – Bulusan Volcano in Sorsogon province spewed ash in a phreatic eruption on Sunday morning, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).

“This is to notify the public and concerned authorities of an ongoing phreatic eruption at Bulusan Volcano,” Phivolcs confirmed in a social media post.


“Alert Level 1 status is now raised over Bulusan Volcano, which means that it is currently in an abnormal condition,” Phivolcs said on its website.

The phreatic eruption started at 10:37 a.m. and lasted for about 17 minutes.

“The event was poorly visible through cloud cover over the edifice although a steam-rich grey plume at least 1 kilometer tall was observed from Juban, Sorsogon and was subsequently observed to drift west,” Phivolcs noted.

Ashfall has been recorded in Juban and Casiguran in Sorsogon.

Based on ground deformation data from continuous global positioning system (GPS) monitoring, the Bulusan edifice has been inflated since February last year.

Electronic tilt monitoring meanwhile showed a “sudden but isolated inflation of the southeast lower slopes only since April 2022.”


“These parameters indicate that volcanic processes are underway beneath the edifice that are likely caused by shallow hydrothermal activity,” said Phivolcs.

Joseph John Perez, division coordinator of the disaster risk reduction and management (DRRM) office of the Department of Education in Sorsogon, said the grayish – white ash plume was observed at around 10:30 a.m.

“All District, alternate and school DRRM coordinators within the areas affected by Bulusan Volcano eruption, possibly Juban, Irosin, Casiguran, Bulusan are instructed to monitor possible impact and damage in schools,” he said.

“Before the eruption, the Bulusan Volcano Network recorded 77 volcanic earthquakes in the past 24-hour observation period,” Phivolcs said.

Entry into the four-kilometer radius permanent danger zone is prohibited, Phivolcs stressed. 

Mt. Bulusan is about 70 kilometers southeast of another active volcano, Mayon Volcano, in Albay province.

On August 18, 2021, Phivolcs downgraded the alert level on Bulusan Volcano from Alert Level 1 to Alert Level 0 (Normal) after a general decline in monitoring parameters.


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