Phivolcs Monitors Increased Seismic Activity at Bulusan Volcano; Public Urged to Stay Vigilant

Manila, The Gulf Observer: The Philippine Institute of Volcanology and Seismology (Phivolcs) reported a notable uptick in seismic activity at Bulusan Volcano in Sorsogon province, with 94 volcanic earthquakes recorded since 3 a.m. Monday.

According to a Phivolcs advisory issued late Monday, the majority of the tremors — 90 weak and shallow volcano-tectonic (VT) earthquakes — were linked to rock fracturing. The remaining four low-frequency volcanic earthquakes were attributed to fluid movement beneath the volcano.

The events were detected within 20 kilometers beneath Bulusan’s edifice, with nearly half of them occurring at shallow depths. While degassing activity at the summit crater and nearby vents remained weak to moderate, the institute emphasized that the seismic uptick may be caused by hydrothermal activity, which can result in short-term pressurization of the volcanic system.

Despite the activity, Bulusan Volcano remains under Alert Level 0 (normal). However, Phivolcs warned that steam-driven or phreatic eruptions may still occur without warning.

In light of the potential hazards, local authorities and the public are strongly advised to avoid the 4-kilometer permanent danger zone, especially around vents located on the south-southeastern slopes. Possible threats include rockfalls, landslides, ballistic projectiles, and small pyroclastic density currents.

Aviation authorities are also urged to caution pilots against flying near the volcano’s summit, as ash emissions from a sudden phreatic eruption could pose serious risks to aircraft.

Phivolcs continues to monitor the situation and will issue updates as necessary.