PHIVOLCS: Very weak to weak emission of white steam-laden plumes occur in Bulusan Volcano

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) on Tuesday monitored a “very weak to weak” emission of white steam-laden plumes at the active vents on the crater and summit area of Bulusan Volcano in Sorsogon.

Despite the observed steam-laden plumes, the PHIVOLCS said Alert Level 0 or normal level is maintained over the volcano.

“Currently, very weak to weak emission of white steam-laden plumes transpires at active vents on the crater and summit area. However, volcanic gas activity within the edifice may potentially trigger steam-driven or phreatic eruption from any of the active vents,” PHIVOLCS said in an advisory.

“Alert Level 0 (Normal) is maintained over Bulusan Volcano but there are chances of steam-driven or phreatic eruptions occurring from the crater or summit area,” it added.

PHIVOLCS said a total of 17 volcanic earthquakes occurred at depths of 0 to 5.2 kilometers beneath the eastern sector of Bulusan since May 7.

It said that these consisted of 11 volcano-tectonic earthquakes that are associated with rock-fracturing and six tornillo events associated with the movement of volcanic gas, which altogether indicate volcanic gas activity is taking place beneath the edifice.

The agency, meanwhile, warned the public that entry into the four-kilometer radius Permanent Danger Zone (PDZ) particularly near the vents on the south-southeastern slopes is prohibited due to the possibility of sudden and hazardous steam-driven or phreatic eruption, rockfall, and landslide.

Civil aviation authorities and pilots were also advised to avoid flying close to the volcano's summit as ash from any sudden phreatic eruption can be hazardous to aircraft, it said.

It added that residents living within valleys and along river or stream channels should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall.

PHIVOLCS said it will continue to monitor the volcano’s condition.

Last January, the agency lowered the alert level of Bulusan Volcano from Alert Level 1 or low-level of unrest to Alert Level 0 or normal level after it returned to normalcy following a “general decline” in monitoring parameters. — Richa Noriega/RSJ, GMA Integrated News