STILL RESTIVE Volcanic smog or “vog” envelops Taal Volcano in Batangas province in this photo taken at 3:30 p.m. from Tagaytay City in Cavite on Sept. 9, 2024. The volcano, which remains under Alert Level 1, records an “upwelling of hot volcanic fluids” in the volcano’s main crater lake, according to the Philippine Institute of Volcanology and Seismology. —PHOTO COURTESY OF SHIELA TAN
LUCENA CITY — At least 26 volcanic earthquakes in Taal Volcano in Batangas province were detected over the last 24 hours, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported on Friday.
The earthquakes were accompanied by a single volcanic tremor that lasted two minutes, Phivolcs said in its bulletin.
Phivolcs defines volcanic earthquakes as those “generated by magmatic processes or magma-related processes beneath or near an active volcano.”
“Unlike tectonic earthquakes that are produced by faulting, volcanic earthquakes are directly produced by many processes and are therefore much more varied in characteristics,” the agency explained.
Volcanic tremors, on the other hand, are “continuous seismic signals with regular or irregular oscillations and low frequencies (typically 0.5–5 Hz) that can last for more than a minute.”
The Phivolcs added: “Tremor can be caused by different processes inside the volcano, including resonance triggered by magma or magmatic gas flowing through cracks and vents, successive overlapping low-frequency earthquakes, and eruptions of magma.”
On Thursday morning, Taal Volcano recorded a five-minute minor phreatic or steam-driven eruption that produced a 1,500-meter-high white plume.
In its latest update, Phivolcs also recorded the emission of 6,307 metric tons (MT) of sulfur dioxide (SO2) from Taal’s main crater, which rose 1,500 meters high before drifting in southwest direction.
The Phivolcs classified the latest spewing activity of the volcano as “voluminous emission.”
However, there was no reported upwelling of hot volcanic fluids in the Main Crater Lake on Taal Volcano Island which sits in the middle of Taal Lake.
No volcanic smog, or “vog,” was also observed during the latest monitoring period.
Taal Volcano is still under alert level 1 (low level of volcanic unrest), Phivolcs said.