66 quakes, 6 tremors recorded at Bulusan Volcano
Children, wearing face masks for protection, pose for the camera on Tuesday, April 29, 2025, as residents and government workers clear roads and rooftops of volcanic ash that fell on Juban, Sorsogon, after the phreatic eruption of Mt. Bulusan on Monday. — Photo from the Sorsogon Provincial Information Office
MANILA, Philippines—In addition to erupting again on Tuesday night, Bulusan Volcano in Sorsogon recorded 66 volcanic earthquakes and six volcanic tremors, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).
Phivolcs’ 24-hour monitoring posted on Wednesday indicated that the volcanic earthquakes and volcanic tremors lasted for one to 163 minutes.
Phivolcs earlier defined volcanic earthquake as an earthquake coming from an active volcano, where it differs from a tectonic earthquake, which is produced from faulting.
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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.”
Meanwhile, the phreatic eruption began at 7:43 p.m. and ended at 9 p.m. Rumbling sounds from the volcano were heard at Cogon, Irosin.
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The volcano also logged one ash emission event that lasted six minutes. This generated a plume 70 meters tall that drifted west to southwest.
Alert level 1, or low-level unrest, remains over the volcano after it erupted on Monday. The volcanic eruption that lasted for around 24 minutes resulted in a bent plume that rose 4,500 meters above the crater before it drifted west to southwest.
