Bulusan now on Alert Level 1

July 7 ------ The Philippine Institute of Volcanology and Seismology (Phivolcs) raised on Monday the alert status of Bulusan Volcano in Sorsogon from Alert Level 0 to Alert Level 1 after an increase in seismic activity was observed in the past days. In its bulletin issued Monday afternoon, Phivolcs said that Alert Level 1 status now prevails over Bulusan which means that the volcano is at a “low level of volcanic unrest.”

According to Phivolcs, Bulusan’s monitoring network recorded a total of 53 volcanic earthquakes since July 3, including 43 low-frequency events that are associated with “weak and shallow hydrothermal or magmatic gas activity within the edifice. State volcanologists said the rise in the seismic activity of Bulusan could be followed by steam-driven or phreatic eruptions at the summit crater or from flank vents on the upper to middle slopes, despite the absence of visible degassing or steaming from the active vent this year.

Ground deformation data from continuous GPS measurements also indicate short-term inflation of the edifice since late February this year, Phivolcs added. These parameters, the agency explained, indicate that volcanic processes are “underway beneath the edifice” which may be caused by “deep-seated degassing or hydrothermal activity or magmatic intrusion.” Following the raising of Bulusan’s danger level, Phivolcs reminded the local government unit and the public that entry into the four-kilometer radius Permanent Danger Zone must be strictly prohibited, while vigilance in the Extended Danger Zone must be exercised due to possibilities of sudden and hazardous phreatic eruptions.

Residents living within valleys and along river or stream channels especially on the southeast, southwest, and northwest sector of the edifice should also be vigilant against sediment-laden stream flows and lahars during heavy and prolonged rainfall, the agency emphasized. Phivolcs added that civil aviation authorities must advise pilots to avoid flying close to the volcano’s summit as ejecta from any sudden phreatic eruption can be hazardous to aircraft. Last January this year, the state volcanology bureau lowered the alert status of Bulusan to Alert Level 0 due to a general decline in monitoring parameters.

Apart from Bulusan, Phivolcs is closely monitoring other active volcanos in the country including Kanlaon and Taal, which are also at Alert Level 1, and Mayon which is currently at Alert Level 2 or at a “moderate level of unrest.”

Source: mb.com.ph