In 3-Day Observation Period: Phivolcs logs 528 Bulusan quakes

By Ernie Delgado

LEGAZPI CITY --- Mount Bulusan in Sorsogon has seen a significant increase in seismic activity since June 12, recording 528 volcanic earthquakes over three days, according to state volcanologists.

In monitoring bulletins from June 13 to 15, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported that this sustained seismic activity, which occurred from 12 a.m. on June 12 to 12 a.m. on June 15, primarily consisted of volcano-tectonic earthquakes.

This indicates that rock is breaking apart deep underground, approximately 5 kilometers below the volcano’s surface, Phivolcs said.

While most of these earthquakes were weak and shallow, the agency warned that these could lead to steam-driven eruptions, also known as phreatic eruptions, that could occur from any of the summit vents.

Phivolcs also noted that degassing from the active vents has ranged from weak to moderate in the past few days, with low levels of volcanic sulfur dioxide emissions recorded on June 11.

Despite the rise in seismic events, Bulusan remains at Alert Level 1, indicating a “low-level unrest.”

Given the situation, Phivolcs has advised the public to avoid entering the four-kilometer-radius Permanent Danger Zone due to the potential for sudden and hazardous steam-driven or phreatic eruptions, as well as risks of rockfalls, landslides, and other volcanic hazards.

Civil aviation authorities should also caution pilots to avoid flying near the volcano’s summit, as ash from any sudden phreatic eruption can pose risks to aircraft.

In the event of phreatic eruptions, communities located to the west and downwind of the volcano should prepare for ashfall.

Officials are urged to pay special attention to vulnerable individuals, including the elderly, pregnant women, infants, and those with medical conditions.

Additionally, residents living in valleys and along rivers and stream channels should be cautious of potential lahar flow following heavy and prolonged rainfall after a phreatic eruption. (PIA Bicol)

BENEATH THE QUIET PEAK Though standing serene against the sky, Mount Bulusan is showing signs of unrest. Over the past three days, 528 volcanic earthquakes were recorded beneath the volcano, most of them caused by rocks breaking deep underground about five kilometers below the surface, according to Phivolcs. The heightened seismic activity serves as a reminder that one of the country’s most active volcanoes remains restless beneath its tranquil facade. Photo courtesy of PIA/Ernie Delgado