Bulusan Volcano Experiencing Increased Seismic Activity
The Bulusan Volcano in Sorsogon is showing signs of heightened seismic activity, according to the Philippine Institute of Volcanology and Seismology (PHIVOLCS). An advisory issued on Sunday noted the volcano’s evolving behavior, signaling vigilance for nearby communities and visitors.
What the Data Shows
From 12 a.m. on Saturday, October 11, PHIVOLCS recorded 72 volcanic earthquakes within the Bulusan Volcano Network. The agency described these events as volcanic-tectonic (VT) earthquakes, which occur due to rock fracturing beneath the volcano. The earthquakes were focused at depths of less than 10 kilometers under the northern sector of Bulusan, suggesting shallow activity tied to the volcano’s subsurface processes.
Degassing and Sulfur Dioxide Emissions
PHIVOLCS also observed ongoing degassing from the volcano’s active vents, ranging from very weak to weak in strength as Bulusan remained visible over recent days. On Thursday, October 9, the volcano emitted an average of 31 tonnes of sulfur dioxide (SO2). Although this value is below the baseline of 200 tonnes per day, it indicates persistent shallow hydrothermal activity beneath Bulusan’s summit.
Alert Level and What It Means
PHIVOLCS has raised awareness with Bulusan Volcano currently at Alert Level 1, indicating low-level unrest. The advisory cautions that there is an increased possibility of steam-driven or phreatic eruptions from the crater or its summit vents, which could occur suddenly and without warning. While a full eruption is not being indicated, the agency stresses that residents and visitors should remain vigilant.
Possible Hazards to Expect
The ongoing activity keeps in mind a range of potential hazards within the four-kilometer Permanent Danger Zone (PDZ) and the 2-kilometer Extended Danger Zone (EDZ) on the southeast flank. PHIVOLCS lists possible outcomes such as pyroclastic density currents (PDCs), ballistic projectiles, rockfalls, snow-like avalanches in certain conditions, and ashfall in surrounding areas. These scenarios underscore the need for prepared communities and regulated access to the PDZ and EDZ.
Safety Guidance for Communities
PHIVOLCS has urged local government units and the public to enforce the PDZ prohibition and exercise heightened caution in the EDZ. For residents experiencing ashfall or exposure to volcanic gases, protective masks or wet cloths are recommended to reduce inhalation risk, especially for vulnerable groups like the elderly, those with respiratory or cardiovascular conditions, pregnant women, and infants. The advisory also highlights the importance of keeping away from the summit and avoiding flights or flying near the volcano to mitigate the dangers posed by sudden phreatic eruptions.
What to Do if You Are Nearby
Staying informed is key. Monitor PHIVOLCS advisories, local government updates, and emergency management guidelines. If ashfall occurs, close windows, seal doors, and wear proper respiratory protection. In case of a rapid change in activity or an eruption warning, follow official evacuation instructions and ensure you’re within a pre-identified safe location away from the PDZ and EDZ.
Looking Ahead
PHIVOLCS will continue to monitor Bulusan’s seismicity, degassing, and gas emissions to detect any escalation in unrest. The public is reminded that volcanic behavior can evolve quickly, and preparedness remains essential for nearby communities and travelers who may be exploring the Sorsogon region.
