(PNA file photo)

MANILA – Although the volcanic earthquakes recorded in Mount Bulusan for the past 24 hours are fewer than the previous day, the volcanic tremors detected have more than doubled, based on the Philippine Institute of Volcanology and Seismology's (Phivolcs) record on Tuesday.

For the past 24 hours, 69 volcanic earthquakes caused by movements or eruptions of magma from the volcano have been recorded, fewer than the 126 volcanic quakes recorded the previous day.

However, 56 volcanic tremors that lasted 19 minutes were detected, higher than the 20 volcanic tremors Phivolcs previously recorded.

Volcanic tremors are earthquakes that could last for more than a minute, hours, or even days. For Mount Bulusan, the volcanic tremors signify hydrothermal activity or boiling of groundwater, according to Phivolcs Director Renato Solidum, Jr.

Meanwhile, sulfur dioxide emission on June 12 was at 4,627 tons.

Voluminous plume emission for the past 24 hours reached 750 meters tall, a bit higher compared to the plume emission 500 meters high the previous day.

Alert Level 1 (low-level unrest) is maintained over the Bulusan Volcano.

Entry into the 4-kilometer radius permanent danger zone must be strictly prohibited, and vigilance in the 2-kilometer extended danger zone on the southeast sector must be exercised due to the increased possibilities of sudden and hazardous phreatic eruptions.

People living within valleys and along river or stream channels, especially on the southeast, southwest, and northwest sector of the edifice, are urged to be vigilant against sediment-laden stream flows and lahars in case of heavy and prolonged rainfall should a phreatic eruption occur.

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

Phivolcs on Monday afternoon said the volcano has remained restive as degassing from its summit vents continues. (PNA)