The Philippine Institute of Volcanology and Seismology (Phivolcs) on Sunday warned of possible steam-driven or phreatic eruptions due to an increase in seismic activity in the Bulusan Volcano in Sorsogon.
In an advisory, the Phivolcs said that a total of 72 volcanic earthquakes have been recorded over the volcano since Saturday. The volcanic earthquakes ‘are associated with rock fracturing and are occurring at depths less than 10 kilometers beneath the northern sector of the volcano.’
The Phivolcs also observed ‘shallow hydrothermal activity’ beneath the volcano such as very weak to weak range of degassing activity from active vents when the volcano was visible, and measurement of average emission of sulfur dioxide of 34 tons per day.
‘Alert Level 1 (low-level unrest) is maintained over Bulusan Volcano, but presently there are increased chances of steam-driven or phreatic eruptions occurring from the crater and/or its active vents on the summit that could occur suddenly and without warning,’ the Phivolcs said.
With this, Phivolcs reminded that entry into the four-kilometer radius Permanent Danger Zone must be prohibited and that flying of aircraft close to the volcano’s summit is not advised.
The agency also recommended vigilance in the two-kilometer Extended Danger Zone on the southeast portion due to possible hazards such as pyroclastic density currents, ballistic projectiles, rockfall, avalanches, and ashfall.
It also said that people living within valleys or along rivers or streams, especially on the western part of the volcano’s edifice, must be vigilant of sediment-laden stream flows and lahars.
‘Communities that experience ashfall must take all necessary precautions and use protective masks or wet cloth to prevent ash inhalation, with special attention given to vulnerable persons including elderly, persons with respiratory or cardio-vascular diseases, expecting mothers and infants,’ Phivolcs added.