(PNA file photo)

MANILA -- An increase in seismic activity or volcanic earthquakes caused by movements or eruptions of magma from the volcano has been observed anew in Mount Bulusan.

The Philippine Institute of Volcanology and Seismology (Phivolcs) on Tuesday reported that 80 volcanic earthquakes have been recorded in Bulusan over the past 24 hours. The figure is much higher compared to only one volcanic quake recorded the previous day.

Late Monday, the Phivolcs said 65 volcanic quakes, including one low-frequency volcanic quake, were recorded in Bulusan from 5 a.m. to 11:45 p.m.

While most of the recorded quakes were weak and shallow events, Phivolcs said this still indicates that a phreatic eruption could occur within the next few hours to the next few days.

Phreatomagmatic eruptions are caused by the interaction of magma and water.

Meanwhile, the sulfur dioxide flux was recorded at 660 tons on June 20.

Moderate plume emissions reached 300 meters high over the past 24 hours. A weaker eruption is based on the height of the plume coming out of the crater.

Bulusan Volcano remains under Alert Level 1 (low level unrest).

Entry into the 4-kilometer radius permanent danger zone must be strictly prohibited and vigilance in the 2-kilometer extended danger zone must be exercised.

Pilots are advised to avoid flying close to the volcano’s summit as ash from the sudden phreatic eruption can be hazardous to aircraft.

Phivolcs likewise reminded the public that sudden steam-driven or phreatic eruptions could occur. (PNA)