3 weeks ago
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THE Philippine Institute of Volcanology and Seismology (Phivolcs) on Monday issued separate notices following increased seismic activities over two active volcanoes — Kanlaon and Bulusan.
Phivolcs director Teresito Bacolcol said that some 72 volcanic earthquakes have been recorded by the Kanlaon Volcano Network between 12 a.m. and 12 p.m. of May 12, 2025.
"Also, a total of 135 volcanic earthquakes have been recorded since 12 a.m., Sunday, including relatively strong volcano-tectonic or VT earthquakes," Bacolcol said.
"VTs are generated by rock fracturing processes and the increase in VT activity strongly indicates progressive rock-fracturing beneath the volcano as rising magma or magmatic gas drives a path towards the surface," he added.
He observed that there has been a decline in the average sulfur dioxide emission from 4,144 tons to 2,114 tons since April this year.
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"These parameters indicate that the blockage of volcanic gas emission may result in pressurization and swelling of the edifice potentially leading to moderately explosive eruption at Kanlaon," the Phivolcs chief added.
Kanlaon Volcano is currently under Alert Level 3.
Bacolcol said Negros Island is in a state of magmatic unrest, and there are increased chances of short-lived moderately explosive eruptions occurring that could generate life-threatening volcanic hazards.
Phivolcs said that a total of 309 volcanic earthquakes were recorded by the Bulusan Volcano Network since 12 a.m., May 8, 2025.
Of these, 287 VT earthquakes associated with rock fracturing occurred at shallow depth less than four kilometers beneath the southeastern edifice of the Sorsogon volcano, the agency said.
Bacolcol said degassing activity from its active vents have been weak to moderate when the volcano is visible for the past days.
"These changes in parameters may indicate the volcano's shallow hydrothermal activity," he said.
At Level 1 (low-level unrest), Phivolcs said there are increased chances of phreatic eruptions.
Phivolcs said concerned local government units and the public are reminded that entry into the six-kilometer radius permanent danger zone (PDZ) of Kanlaon Volcano and four-kilometer PDZ of Bulusan Volcano must be strictly prohibited.
Furthermore, Bacolcol said that people living within valleys and along river/stream channels should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall should phreatic eruption occur.
