Bulusan logs 14 volcanic quakes, 1 tremor 鈥� Phivolcs
Ash blankets homes, farms and roads in the towns of Irosin and Juban in Sorsogon province after the second phreatic or steam-driven eruption of Bulusan Volcano on April 29, 2025, as seen in this drone shot from the inspection of the provincial government on May 1. — Photo from Sorsogon Provincial Information Office
MANILA, Philippines — Bulusan Volcano in Sorsogon was rocked by 14 volcanic earthquakes and one volcanic tremor during the 24-hour monitoring of the Philippine Institute of Volcanology and Seismology (Phivolcs).
The monitoring posted on Friday said that the volcanic tremor lasted for 39 minutes.
Phivolcs earlier defined a volcanic earthquake as one that originates from an active volcano, which differs from a tectonic earthquake, which is produced from faulting.
READ: Heavy ashfall affects thousands in Sorsogon as Bulusan erupts
Meanwhile, a volcanic tremor is “a continuous seismic signal with regular or irregular sine wave appearance and low frequencies (0.5 to 5 Hz) where a tremor can be caused by magma flow, low-frequency earthquakes, or minor eruptions.”
The volcano also released 748 tons of sulfur dioxide on Friday, which is more than the 406 tons it emitted the day before.
It generated a plume that rose 100 meters high, and drifted west. The volcano edifice was observed to be inflated.
READ: Seismic activities of Bulusan, Kanlaon volcanoes increased — Phivolcs
Phivolcs observed an increase in the volcano’s activity last Monday where it detected 309 volcanic earthquakes since midnight of May 8.
The volcano had a phreatic eruption last April 29, while its eruption last April 28 prompted its alert level hike from Alert Level from zero (normal) to one (low-level unrest).
Phivolcs prohibits entry into the four-kilometer radius of the permanent danger zone and flying of any aircraft close to the volcano.
The state volcanologist also warned of possible hazards such as sudden steam-driven or phreatic eruptions. /das/abc
