Increased seismic activity recorded at Bulusan volcano, Philippines
A total of 49 volcanic earthquakes were recorded at Bulusan volcano in Sorsogon Province, Philippines, between 03:00 LT on February 26 and 11:00 LT on March 2, 2026, prompting authorities to issue an advisory on increased seismic activity. Sixteen of the events were classified as volcano-tectonic earthquakes occurring at depths of 3–6 km (1.9–3.7 miles) beneath the northern and southeastern flanks of the volcano. Alert Level 0 remains in effect, but officials warn of a possible sudden phreatic eruption.
Image credit: Sorsogon PIO
A total of 49 volcanic earthquakes were recorded at Bulusan volcano between 03:00 LT on February 26 and 11:00 LT on March 2, according to the Philippine Institute of Volcanology and Seismology (PHIVOLCS).
Sixteen of these events were classified as volcano-tectonic (VT) earthquakes generated by rock fracturing at depths of 3–6 km (1.9–3.7 miles) beneath the northern and southeastern portions of the volcanic edifice.
Despite the increase in seismicity, PHIVOLCS maintains Alert Level 0 over the volcano, indicating that no magmatic eruption is forecast. The agency stated that all other monitored parameters remain within background levels.
Degassing activity from the summit crater and active vents has been described as weak to moderate when visibility permits. The most recent sulfur dioxide (SO2) measurements conducted on February 26 indicated emission levels too low to be detected.
PHIVOLCS said the recent increase in seismicity may indicate that hydrothermal processes beneath the volcano are underway and could lead to a sudden steam-driven, or phreatic, eruption. Such eruptions occur when groundwater is rapidly heated by hot rock or magma at depth, producing explosive steam expansion without new magma necessarily reaching the surface.
Bulusan volcano, located in Sorsogon Province in the Bicol Region of southern Luzon, rises to 1 565 m (5 135 feet) above sea level and is one of the country’s most active volcanoes. Its eruptive history is dominated by short-lived phreatic explosions that can generate ash plumes, ballistic fragments, and localized ashfall.
Although Alert Level 0 remains in place, PHIVOLCS reminded the public that entry into the 4 km (2.5 miles) radius Permanent Danger Zone (PDZ) is prohibited due to the possibility of sudden phreatic eruptions, rockfall, and landslides. The advisory specifically highlighted vents on the south-southeastern slopes as areas of elevated hazard.
Local government units were advised to review emergency and contingency plans in case the alert level is raised to Alert Level 1. Civil aviation authorities were also advised to caution pilots against flying close to the volcano’s summit because ash from a sudden phreatic eruption can pose hazards to aircraft.
References:
1 BULUSAN VOLCANO ADVISORY – PHIVOLCS – March 2, 2026
I’m a science journalist and researcher at The Watchers, contributing to the Epicenter edition, where I cover peer-reviewed scientific research and emerging discoveries across Earth and space sciences. With a background in astronomy and a passion for environmental science, I’ve worked in shark and coral conservation in Fiji, conducting reef and shark-behavior research, contributing to mangrove restoration, and earning PADI Open Water and Coral Reef Certifications. I bring a blend of scientific rigor and storytelling to illuminate the discoveries shaping our planet and beyond.
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