Photo courtesy of Philippine News Agency (PNA).
State volcanologists continued to monitor Taal Volcano in Batangas after it showed renewed signs of unrest, with 75 volcanic tremor events recorded in the past 24 hours.
The Philippine Institute of Volcanology and Seismology said in its Sunday, July 5 bulletin that the tremors lasted from one to three minutes each.
Phivolcs, however, did not detect any volcanic earthquake during the same monitoring period.
The latest figure came after Taal registered 61 volcanic earthquakes and 60 volcanic tremors a day earlier, reflecting persistent activity beneath the volcano.
The recent unrest followed several days of weaker seismic activity. Phivolcs had recorded four volcanic earthquakes on Friday, two on Thursday, and 19 volcanic earthquakes with five tremor events on July 1.
Volcanic earthquakes are caused by internal processes within an active volcano and are identified through specific seismic features, including waveform patterns, amplitude, and wave periods.
Volcanic tremors, on the other hand, are continuous low-frequency signals that may occur in steady or irregular patterns. These are often associated with the movement of magma, volcanic gas, or other fluids under the volcano.
Phivolcs also measured sulfur dioxide emissions from Taal at 829 metric tons per day, which it classified as moderate.
The agency reported no observed upwelling of hot volcanic fluids in the main crater on Taal Volcano Island. No volcanic smog, or vog, was also observed during the monitoring period.
Taal Volcano remains under Alert Level 1, which indicates low-level unrest.
Phivolcs reminded the public that Alert Level 1 does not mean the volcano has returned to normal. It said Taal remains in an abnormal condition and could still generate sudden steam-driven explosions or other volcanic activity.