Sorsogon City, Sorsogon — Mount Bulusan, here, exhibited two phreatic eruptions, spewing steam and ash at 11:02 a.m. and 11:20 a.m. yesterday due to a build-up of gas inside the volcano, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported.
Phivolcs Director Renato Solidum, speaking in Quezon City, said the first explosion lasted 10 minutes and produced a “one-kilometer-high steam and ash column.”
In Sorsogon, Phivolcs resident volcanologist Ed Laguerta described how it produced a grayish steam and ash plume which drifted west-southwest, accompanied by a rumbling sound heard by local residents of Cogon in Irosin town.
The second event, Laguerta said, was smaller and lasted for about one minute based on seismic record. He added that the volcano remains at Alert Level 1.
Solidum said yesterday’s ash explosions are typical of Mt. Bulusan during restive periods, when its hydrothermal system is disturbed or when steam accumulates and pressurizes.
Steam-driven explosion, also called phreatic explosions, happens when groundwater comes into contact with magma. When it heats up the water, it then becomes steam. It builds up pressure and pushes its way through the volcano crater.
The event can also be compared to a well-shaken soda fizzing out of a bottle.
MANILA BULLETIN
