LEGAZPI CITY, June 16 (PNA) — Based on past records, more explosions can be expected to occur with varying intensity, duration and distribution of ash after Mount Bulusan in Sorsogon erupted twice on Tuesday, spewing an ash plume cloud that went as high as 500 meters from the summit, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) said.
Latest recorded eruptions took place in Nov. 2010 until May 2011.
Celso Mancilla, Phivolcs science research assistant, said the eruption was a phreatic- type explosion that sent ash plumes ranging from 400 to 500 meters high.
In a phone interview, Mancilla said the first phreatic eruption was recorded to have occurred at 11:02 a.m. Tuesday and was followed by another eruption at 11:20 a.m.
Mount Bulusan belched a gray ash plume cloud that drifted west-southwest of the volcano — affecting the towns of Juban, Irosin and Casiguran.
Classes were suspended in the villages of Juban town where ash falls were mostly felt, said Benny Recibido, Philippine Information Agency provincial manager.
Mancilla said he could not yet say what villages were affected by the ash fall, adding that Phivolcs personnel led by Crispulo Deolata, Phivolcs resident volcanologist, are currently conducting assessment.
Phivolcs records indicate that phreatic eruptions are typical to Bulusan during restive periods, when its hydrothermal system is disturbed or when steam accumulates and pressurizes at the shallow levels of the volcanic edifice.
The Office of Civil Defense, quoting a report from the National Disaster Risk Reduction and Management Council, said the eruption was accompanied by an explosion-type earthquake with rumbling sounds.
Hours before the eruption, Phivolcs Bulusan bulletin as of 8:00 a.m. Tuesday, said seismic monitoring network detected five volcanic earthquakes during the past 24-hours.
Weak emissions of white steam plumes were observed to drift and crept down slope of the volcano, while a very slight inflation was observed of the volcano’s edifice.
Alert Level 1 (abnormal) remains in effect over the volcano.
The public is warned not to enter the four-km permanent danger zone due to the possibility of sudden and hazardous steam-driven or phreatic eruption. (PNA)