By Ma. Cristina Arayata
MANILA – Bulusan Volcano is now back to normal level or Alert Level 0, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported.
In an advisory Wednesday night, Phivolcs said the observational parameters have returned to baseline or background levels.
No magmatic eruption is also foreseen in the immediate future, prompting Phivolcs to lower the volcano’s alert status.
Since the first week of December, Phivolcs has been recording zero to five earthquakes at Bulusan Volcano per day.
Most of these earthquakes occurred at a shallow depth of less than 10 kilometers beneath the edifice.
The decrease indicates that rock-fracturing processes within the volcano associated with shallow hydrothermal activity have diminished.
The average sulfur dioxide emission was 274 tonnes per day since Oct. 12, 2022, with the highest average emission recorded at 462 tonnes last Oct. 21.
“Volcanic gas input from the shallow hydrothermal system has generally remained within baseline level,” the advisory read.
It added that most monitored springs have been exhibiting overall slight increases in acidity and decreases in temperatures and diffuse carbon dioxide but do not indicate input from deep magma sources.
Phivolcs also said very weak to weak emission has been observed from the active vents of the volcano since the second week of November.
Despite Bulusan Volcano being back to its normal state, the entry into the four-kilometer radius permanent danger zone, particularly near the vents on the south southeastern slopes, should be avoided due to the possibility of sudden and hazardous steam-driven or phreatic eruption, rockfall and landslide.
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.
Those residing in valleys and along the river/stream channels, on the other hand, are advised to be vigilant against sediment-laden stream flows and lahars during heavy and prolonged rainfall. (PNA)