Sorsogon braces for lahar flow after blast

LEGAZPI CITY—Disaster-response agencies in Sorsogon province have started preparing for possible lahar flows during heavy rain following the eruption of Mt. Bulusan on Friday.

At least 12 villages in the towns of Juban, Casiguran and Irosin are on the path of lahar should it flow along Cadac-an River, said Raden Dimaano, chief of the Provincial Disaster Risk Reduction and Management Office (PDRRMO).

“We have already identified the evacuation areas of residents [who might be affected by lahar flows]. Our early warning protocols are also in place,” Dimaano said.

The Philippine Institute of Volcanology and Seismology (Phivolcs), however, is expecting minimal lahar flow around the volcano. It has yet to determine the volume of deposits from Bulusan’s latest blast.

“In Bulusan, particularly in this previous phreatic (steam-driven) explosion, ashes were not concentrated [on a particular area] and its volume was very minimal,” resident volcanologist Eduardo Laguerta said. “In Mayon Volcano, there is pyroclastic flow concentrated on the gully [down] to river channels.”

The volcano remains “restive” after it spewed out a 2-kilometer high ash plume on Friday, Laguerta said. “Based on our past observations … after an explosion, it will rest for weeks or months,” he said.

On Sunday, Phivolcs said three volcanic quakes were recorded around Bulusan for the past 24 hours. Five quakes, including an explosion-type tremor, were noted in the first 24-hour period of monitoring on Friday.

Alert Level 1 was raised after the volcano spewed ash over 19 villages in Casiguran and Juban.

Laguerta said the collected volcanic ashes would be tested for magma fragments to better understand the status of the volcano.

“If the test finds that it contains juvenile magma fragments, this would mean that magma is building up and this may be a precursor to a much stronger eruption,” he said.