Six volcanic earthquakes, including an explosion-type tremor, were recorded by the Philippine Institute of Volcanology and Seismology in Mount Bulusan in the past 24 hours after it spewed steam Friday afternoon.
According to Phivolcs, Mount Bulusan generated a steam-driven explosion accompanied by a rumbling sound at 4:54 p.m. Friday.
Based on its seismic record, the event lasted for approximately four minutes and produced approximately 1,500-meter high dark gray ash plume that drifted towards the northeast.
Ash fall was reported in Casiguran, Gubat, and Barcelona, Sorsogon.
In its 24-hour monitoring, Mount Bulusan’s seismic monitoring network recorded six volcanic earthquakes, including the explosion-type earthquake last Friday. However, steaming activity could not be observed due to thick clouds covering the summit.
Alert Level 1, which means the volcano is under abnormal state, remains in effect over Mount Bulusan.
Phivolcs said this indicates that hydrothermal processes are underway beneath the volcano that may lead to more steam-driven eruptions.
The local government units and the public were reminded that entry to the four-kilometer permanent danger zone is strictly prohibited due to the possibility of sudden and hazardous steam-driven or phreatic eruptions.
Civil aviation authorities were also asked to advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft.
Likewise, people living within valleys and along river and stream channels, especially on the southwest and northwest sector of the edifice, should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall. (Ellalyn B. de Vera)