Increased seismicity observed in Bulusan for 3rd time this month

Magnitudes ranged from 0.3 to 2.2 and were generated between 1 to 9 kilometers beneath the north to northwestern flank of the volcano edifice. (File photo by Chris Newhall, (U.S. Geological Survey), Public Domain)

MANILA – An increase in seismicity has been observed in the Bulusan Volcano for the third time this January, indicating magmatic processes that may lead to steam-driven or phreatic eruptions.

In an advisory Sunday night, the Philippine Institute of Volcanology and Seismology (Phivolcs) said 126 weak volcano-tectonic earthquakes were recorded since 12 a.m. of the same day.

Magnitudes ranged from 0.3 to 2.2 and were generated between 1 to 9 kilometers beneath the north to northwestern flank of the volcano edifice.

Phivolcs earlier reported an increase in Bulusan’s seismic activity on Jan. 11 and 23.

“Sustained seismic unrest for the past month indicates persistent hydrothermal activity that is likely driven by deep-seated magmatic processes and may lead to steam-driven or phreatic eruption,” the advisory read.

Meanwhile, very weak to moderate plumes from the summit crater and active vents were also observed.

Alert Level 1 prevails over Bulusan Volcano, which means it is currently at low-level unrest with increased chances of steam-driven or phreatic eruptions.

Local government units and the public are also reminded that entry into the 4-kilometer radius permanent danger zone should be prohibited.

Vigilance in the 2-kilometer extended danger zone on the southeast sector must be exercised due to the possibilities of sudden and hazardous phreatic eruptions.

Aviation authorities are urged to advise pilots to avoid flying close to the volcano’s summit, as ash from any sudden phreatic eruption can be hazardous to aircraft.

“We continue to monitor Bulusan Volcano, and will immediately inform the public of any significant changes in the parameters,” Phivolcs Director Teresito Bacolcol said Monday.