LEGAZPI CITY, Albay: Mount Bulusan in Sorsogon erupted again on Wednesday morning, causing heavy ashfall, a day after the Philippine Institute of Volcanology and Seismology (Phivolcs) warned the public and disaster officials of possible explosion of the restive volcano.
The eruption prompted the Municipal Disaster Risk Reduction Management Office (MDRRMO) to recommend suspension of classes in all levels in Bulusan town.
The Phivolcs recorded a steam-driven or phreatic eruption at 4:58 a.m. from vents on the volcano’s southeastern upper slope.
The minor eruption was recorded as an explosion-type earthquake that lasted for nine minutes based on the seismic record, Ed Laguerta, Phivolcs resident chief volcanologist in Bicol, said.
Visual observation of the volcano was obscured by a thick cloud cover but limited observations near the vent approximated the eruption plume to have risen one kilometer high.
This was the third time that Bulusan volcano exploded this month, the first one was recorded on October 6 and then on Monday.
For the past 24 hours, a Phivolcs bulletin showed that Bulusan’s seismic monitoring network recorded 28 volcanic earthquakes while sulfur dioxide (SO2) emission was measured at an average of 176 tons.
Laguerta said Mount Bulusan continuously indicates slight inflationary changes of the edifice based on precise leveling data since August this year.
Similar inflationary trends were also recorded by continuous GPS measurements on September 30, indicating pressurization beneath the volcano’s edifice.
Meanwhile, alert level 1 remains in effect over Mount Bulusan, indicating that hydrothermal processes are underway beneath the volcano that may lead to more steam-driven or phreatic eruptions, Laguerta said.
The Phivolcs strictly reiterated the no-entry warning within the 4-kilometer radius Permanent Danger Zone (PDZ) and in the Extended Danger Zone (EDZ), warning of increased possibilities of sudden and hazardous phreatic eruptions.
Similarly, Phivolcs officials warned residents living within valleys and along river or stream channels especially on the southeast, southwest and northwest sectors of the volcano’s edifice to be vigilant against sediment-laden stream flows and lahar in case of heavy and prolonged rainfall.
Civil aviation authorities were told to advise pilots to avoid flying close to the volcano’s summit as ash from sudden phreatic eruptions can be hazardous to aircraft.