Increased seismic activity recorded in Bulusan Volcano anew – Phivolcs

MANILA, Philippines — The Philippine Institute of Volcanology and Seismology (Phivolcs) on Wednesday said increased seismic activity has been recorded at Bulusan Volcano in Sorsogon.

Phivolcs issued the advisory after a total of 101 volcano-tectonic (VT) earthquakes were recorded in Bulusan since 4:50 a.m. on Wednesday.

According to Phivolcs, these VT events were generated by rock fracturing, which mostly originated within 2.5 kilometers beneath the northern edifice of Bulusan Volcano.

Meanwhile, Phivolcs noted that degassing activity from the summit crater and active vents has been “very weak to moderate,” while volcanic sulfur dioxide emission has remained at low levels and averaged 75 tons/day as of April 9.

READ: Bulusan Volcano in Sorsogon under Alert Level 1

“The increase in volcanic earthquake activity could indicate shallow hydrothermal processes beneath the volcano, which could lead to steam-driven or phreatic eruptions at any of its summit vents,” Phivolcs said.

With this, Phivolcs said Alert Level 1 or low-level unrest remains raised over Bulusan Volcano, with increased seismic activity signaling increased chances of phreatic eruptions from any of its summit vents.

Under this alert level, entry into the 4-kilometer radius permanent danger zone is prohibited, while the public is urged to exercise vigilance in the 2-kilometer extended danger zone in the southeast sector due to the possible impacts of volcanic hazards such as pyroclastic density currents or PDCs, ballistic projectiles, rockfall, avalanches, ashfall, and others on these danger areas.

“Communities west and downwind of the volcano are also advised to prepare for ashfall in case a phreatic eruption occurs, paying special attention to vulnerable members of the community, including the elderly, expecting mothers, infants, and those with medical conditions,” Phivolcs added.

People living within valleys and along river stream channels, especially on the western sectors of the edifice, on the other hand, were told to be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall, should a phreatic eruption occur.

Furthermore, Phivolcs also called on civil aviation authorities to advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft. /cb /atm