The Philippine Institute of Volcanology and Seismology has raised the unrest status of Bulusan Volcano in Sorsogon province from Alert Level 0 (normal) to Alert Level 1 (low-level unrest) following a series of volcanic earthquakes. 

In its volcanic bulletin, Phivolcs said the Bulusan Volcano Network has recorded 121 volcanic earthquakes since 14 October, 37 of which were volcano-tectonic tremors that are associated with rock fracturing processes at depths of 1-9 kilometers beneath the northwestern and southern slopes of the volcano edifice. 

Phivolcs has also observed ground deformation and inflation or swelling of the Bulusan's southern flank since February, and the northeastern flank has been swelling since September. 

Bulusan also logged an increase in the volcanic carbon dioxide concentration from June to August, and the spring temperature also increased since February. 

Phivolcs said these volcanic activities indicate that hydrothermal activity driven by deep-seated magma degassing may be occurring beneath the volcano and may lead to steam-driven eruptions at any of its summit vents.

It said that Mt. Bulusan is currently in a state of low-level unrest. 

Hence, Phivolcs warned the public that entering int 4-km radius permanent danger zone should be prohibited and vigilance in the 2-km extended danger zone in the southeast sector must be exercised due to the increased possibility of sudden and hazardous phreatic eruptions from the summit crater and/or lateral vents. 

Flying close to the volcano's summit is not allowed as ash from sudden phreatic eruptions can be hazardous to aircraft. 

People living within valleys and along river or stream channels, especially on the southeast, southwest and northwest sectors of the volcano, should be vigilant against sediment-laden stream flows and lahar in the event of heavy and prolonged rainfall should a phreatic eruption occur.