Taal Volcano sees surge in seismic activity
A small cloud of steam rises from Taal Volcano, as seen from Tagaytay City. —ROBERT JAWORSKI L. ABAÑO
LUCENA CITY — After a brief lull, Taal Volcano in Batangas province recorded a notable increase in seismic activity, logging 71 volcanic earthquakes over the past 24 hours, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported Monday, May 5.
According to Phivolcs’ morning bulletin, the earthquakes were accompanied by 11 volcanic tremors, each lasting one to two minutes.
The uptick follows a quieter trend from earlier this month: 40 quakes and six tremors were recorded on May 3; 36 quakes and five tremors on May 2; and 74 earthquakes and four tremors on May 1.
In April, the volcano registered 283 volcanic earthquakes and 55 tremors, the agency noted.
Phivolcs said the data indicate ongoing magmatic activity beneath or near the volcano.
Volcanic earthquakes, the agency explained, are “generated by magmatic processes or magma-related processes beneath or near an active volcano.” Unlike tectonic quakes, which result from faulting, volcanic quakes stem from more varied processes.
Volcanic tremors, meanwhile, are described as “continuous seismic signals with regular or irregular oscillations and low frequencies (typically 0.5 to 5 Hz) that can last for more than a minute.” These may be triggered by magma or magmatic gas flowing through cracks and vents, overlapping low-frequency earthquakes, or magma eruptions.
Despite the increased activity, Taal Volcano remains under Alert Level 1, which indicates low-level unrest. Phivolcs cautioned that the classification does not mean the volcano is no longer in an abnormal state or that the threat of eruption has disappeared.
In its latest update, the agency also reported a moderate emission of sulfur dioxide (SO₂), estimated at 1,200 metric tons. The gas plume rose 1,200 meters from the main crater and drifted southward.
No volcanic smog (vog) or upwelling of hot fluids in the main crater lake was observed during the monitoring period.
Located in the middle of Taal Lake, Taal Volcano is the Philippines’ second most active volcano, with 38 recorded historical eruptions.
READ: Taal Volcano jolts Batangas with 74 quakes, 4 tremors in 24 hours
