Authorities may Raise Bulusan Volcano’s Alert Level to 2

(PNA) — Authorities may raise the alert level on Bulusan volcano’s activity from 1 to 2 if it intensifies.

When asked if the series of phreatic explosions on Tuesday morning is a precursor of bigger eruptions, Ed Laguerta, Philippine Institute of Volcanology and Seismology (Phivolcs) Bicol resident volcanologist, said that if a change in chemical composition happens, the possibility of stronger volcanic activity is likely to take place.

The Bulusan volcano’s restive condition intensified when two explosions occurred in a span of 18 minutes on Tuesday.

Following the heightened unrest of the Bulusan volcano, the Phivolcs warned of a possible stronger Bulusan volcano activities.

On Tuesday, the volcano had two steam-driven explosions at 11:02 a.m. and 11:20 a.m.

The first event lasted for approximately 10 minutes and produced a one-kilometer high grayish steam and ash plume which drifted towards the west-southwest direction.

This was accompanied by a rumbling sound heard by local residents of Barangay Cogon in Irosin at the west-southwest slopes of the volcano.

The second event was smaller and lasted for about one minute, based on seismic record.

The explosions, according to Laguerta, were bigger than the previous eruptions last month.

An explosion-type earthquake associated with rumbling sound took place while the emitted ash fell on the volcano’s southwest quadrant, affecting the municipalities of Juban and Irosin.

The Bulusan volcano in Sorsogon, located some 70 km southeast of the Mayon volcano in Albay, is one of the country’s most active volcanoes.

Last month, the volcano exploded twice — first on May 1 and then on May 6.

A Bulusan eruption is different from that of the Mayon volcano.

Usually, Bulusan’s explosion is phreatic or steam-driven while that of Mayon is magmatic.

Bulusan volcano’s last magmatic explosion occurred 40 years ago.

A phreatic eruption occurs when water makes contact with hot rocks inside the volcano, causing steam.

Due to pressure build-up, the steam escapes through the crater explosively.

Such explosion is typical of Bulusan during its restive periods when its hydrothermal system is disturbed or when steam accumulates and pressurizes at the shallow levels of the volcanic edifice, Laguerta explained.

The hydrothermal process may now be underway beneath the volcano that may lead to more steam-driven eruptions.

The Bulusan volcano is on alert level 1 after a series of explosions last month due to hydrothermal abnormalities beneath it.

The Phivolcs warned the public and disaster officials to be on guard 24/7 for more steam-driven or phreatic eruptions in the coming days.

Col. Ceasar Idio, commanding officer of the Army’s 903rd Infantry Brigade, said military trucks are on standby for possible evacuation of residents living in the slopes of the restive volcano.

The Army’s disaster response team is also on standby and ready to respond when the need arises.

“My men belonging to disaster response units are on alert and ready for possible evacuation of the residents living in danger zone,” Idio said.

The Phivolcs warned the public not to venture within the four kilometer danger zone as explosion may happen anytime following the restive condition of Bulusan volcano.

Civil aviation authorities also advised pilots to avoid flying close to the volcano’s summit as ejecta due to sudden phreatic eruption can be hazardous to aircraft. (PNA) FFC/FGS/RBB/CBD/PJN