Taal Volcano in Batangas recorded six volcanic earthquakes and a single prolonged tremor in the past 24 hours, indicating a decline in seismic activity, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported Tuesday, Sept. 1.
In its latest bulletin, Phivolcs said the volcanic tremor lasted 420 minutes. Despite its duration, the agency said there was no immediate cause for alarm, noting that volcanic tremors are a normal occurrence at Taal.
The latest seismic activity marked a notable decline from the previous nine days, from Aug. 20 to 28, when Taal recorded double-digit numbers of volcanic earthquakes daily, for a total of 229 earthquakes and 12 tremor episodes.
On Aug. 29, Taal recorded eight volcanic earthquakes, another eight the following day, and 13 on Aug. 31.
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, meanwhile, are continuous seismic signals with regular or irregular oscillations and low frequencies, typically ranging from 0.5 to 5 hertz, that can last for more than a minute.
Despite the decline in seismic activity, Taal continued to emit sulfur dioxide. Phivolcs recorded 381 metric tons of SO2, although the emission level remained classified as ‘weak.’
The agency also reported no observed upwelling of hot volcanic fluids in the Main Crater Lake and no volcanic smog, or ‘vog,’ during the monitoring period.
On Saturday (August 29), Phivolcs warned of possible lahar flows and volcanic debris around Taal and Mount Pinatubo amid prolonged heavy rains brought by the southwest monsoon, or ‘habagat.’
Heavy rainfall may trigger muddy streamflows and volcanic debris flows around Taal Volcano, particularly along the western and northern slopes of Taal Lake.
These hazards could affect parts of Batangas, particularly the municipalities of Agoncillo, Laurel, and Talisay.
Phivolcs advised communities in potentially affected areas to closely monitor weather conditions and take necessary precautionary measures.
Taal Volcano remains under Alert Level 1, indicating a low level of volcanic unrest.