The Philippine Institute of Volcanology and Seismology (PHIVOLCS) on Monday reported heightened seismic activity at Bulusan Volcano in Sorsogon, recording a total of 49 volcanic earthquakes since February 26.
In a social media advisory, the agency said 16 of the tremors were classified as volcano-tectonic earthquakes.
“Of these (volcanic earthquakes), sixteen were volcano-tectonic earthquakes associated with rock fracturing between 3 to 6 kilometers beneath northern and southeastern edifice of Bulusan Volcano,” the bureau said.
Despite the spike in seismic events, PHIVOLCS noted that other monitoring parameters remain at background or very weak levels. These include degassing activity — a possible indicator of rising magma — and volcanic sulfur dioxide emissions.
The volcano remains under Alert Level 0, which means that no magmatic eruption is currently expected.
However, PHIVOLCS advised local government units to stay prepared in case conditions change, urging officials to “prepare their response and revisit their emergency plans” should the alert level be raised.
Authorities reiterated that entry into the 4-kilometer permanent danger zone is strictly prohibited due to the risk of sudden volcanic activity.
Based on previous PHIVOLCS data, Bulusan’s last recorded eruption occurred on April 28–29 last year, when a phreatic eruption lasted approximately 24 minutes.