The Philippine Institute of Volcanology and Seismology (Phivolcs) raised Alert Level 1, indicating low-level unrest, at Mount Bulusan in Sorsogon after its phreatic eruption early Monday morning, which prompted extensive road clearing operations in affected areas.
The volcano erupted at 4:36 a.m., lasted for 24 minutes and sent a plume of ash 4,500 meters above the summit, according to the state seismic agency. The ash drifted west-southwest across nearby areas, affecting several barangays in Sorsogon province.
The eruption followed a series of volcanic earthquakes—53 in total over the past 24 hours. Local officials reported hearing rumbling sounds 15 minutes prior to the eruption, which were detected by infrasound sensors.
In addition to the ashfall, a pyroclastic density current (PDC), or “uson,” descended the southwestern slopes, traveling up to three kilometers from the summit.
Ashfall was reported in multiple areas, including Barangays Cogon and Bolos in Irosin; Puting Sapa, Guruyan, and Buraburan in Juban; and Tulatula Sur in Magallanes.
Phivolcs strongly advised the public to avoid entering the four-kilometer permanent danger zone around Bulusan, where the risk of further phreatic eruptions remains high.
As part of the ongoing response, authorities launched road clearing operations in Barangay Buraburan, Juban, where volcanic ash has accumulated on local roads.
The Sorsogon Provincial Government, Bureau of Fire Protection (BFP), Philippine National Police (PNP), and Sorsogon Provincial Disaster Risk Reduction and Management Council (SPDRRMC) are working together to clear the national highway.
Governor Boboy Hamor urged motorists to avoid affected roads while the clearing operations are underway and emphasized the importance of public safety and vigilance.
“The cleaning of the national highway in Barangay Buraburan, Juban, where thick ash from the volcanic eruption has fallen, is currently being given particular attention,” the Sorsogon Public Information Office said Monday.
Residents in affected areas are advised to wear protective masks or use wet cloths to prevent inhalation of harmful ash particles.
Phivolcsh also warned about the potential for lahars and sediment-laden stream flows in valleys and along river channels, particularly in the southeast, southwest, and northwest sectors of the volcano. Heavy rainfall could trigger these hazards in the event of future volcanic activity.
Civil aviation authorities have likewise been instructed to advise pilots to avoid flying near Bulusan, as the risk of encountering volcanic ash clouds is significant during eruptions.
