LEGAZPI CITY, Philippines — State seismologists have lowered to zero the alert level of Bulusan Volcano in Sorsogon after it sustained the decline in its abnormal parameters.
The Philippine Institute of Volcanology and Seismology (Phivolcs) said the zero alert level was hoisted over Bulusan starting at 6 p.m. on Sunday.
Phivolcs said Bulusan registered a general decline in monitoring parameters.
The frequency of volcanic earthquakes decreased to baseline levels or from zero to five quakes per day since the third week of July.
“This indicates that rock fracturing within the volcanic edifice associated with shallow hydrothermal activity has diminished,” Phivolcs said.
Sulfur dioxide emission from Bulusan also decreased from an average of 1,900 tons per day between June 5 and 12 to 230 tons per day between July 25 and Aug. 6.
“The diminishing concentration of sulfur dioxide indicates the depletion of volcanic gas input to the active shallow hydrothermal system,” seismologists said.
Phivolcs said that degassing activity from the volcano’s active vents diminished from weak to moderate emission of steam-laden plumes.
“If a renewed increase in any one or combination of the above monitoring parameters occurs, the alert status may be raised again to Level 1.”
Entry within the volcano’s four-kilometer-radius permanent danger zone remains prohibited due to the possibility of sudden and hazardous steam-driven or phreatic eruptions, rockfalls and landslides.
Meanwhile, in Albay, no earthquakes have been recorded around Mayon Volcano until yesterday, or almost 24 hours after its status was raised back to Alert Level 1 on Sunday afternoon.
“However, Mayon’s sulfur dioxide emission was above the baseline level of 500 tons per day. A slight inflation has been observed in the past 24 hours,” Phivolcs said.