Alert Level 1 up over Bulusan; phreatic eruption observed

MANILA, April 28 ------ A 24-minute phreatic eruption occurred from the summit crater of Bulusan Volcano at 4:36 a.m. Monday, prompting authorities to raise the volcano's alert status from Level 0 (normal) to Level 1 (low-level unrest). The eruption produced a bent plume that rose 4,500 meters above the crater before drifting west to southwest. 

Ashfall was reported in Barangays Cogon and Bolos in the municipality of Irosin and Barangays Puting Sapa, Guruyan, Buraburan, and Tulatula Sur in Juban town, both in Sorsogon province, the Philippine Institute of Volcanology and Seismology (Phivolcs) said. 

Pyroclastic density current (PDC) descended the southwestern slopes and traveled within three kilometers from the summit vent. Phivolcs said rumbling sounds were reported by local government officials approximately 15 minutes before the eruption and were recorded by infrasound sensors. "Prior to the eruption, a total of 53 volcanic earthquakes were recorded over the 24-hour period yesterday," Phivolcs said in its 7 a.m. volcano bulletin on Monday. 

At alert Level 1, the volcano is in low-level unrest with chances of phreatic eruptions. Entry into the four-kilometer radius permanent danger zone (PDZ) must be strictly prohibited. Vigilance in the two-kilometer extended danger zone (EDZ) in the southeast sector must be exercised due to the possible impacts of volcanic hazards such as PDCs, ballistic projectiles, rockfall, avalanches, and ashfall on these danger areas. "Communities that experience ashfall must take all necessary precautions and use protective masks or a wet cloth to prevent ash inhalation," Phivolcs advised. 

People living within valleys and along river/stream channels especially on the southeast, southwest, and northwest sectors of the edifice should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall should phreatic eruption occur. Aviation authorities, meanwhile, must advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft.  

Source: pna.gov.ph