The Philippine Institute of Volcanology and Seismology (Phivolcs) on Wednesday, June 2, warned that volcanic sediment flows or lahars may occur in waterways around Taal and Pinatubo Volcanoes due to Tropical storm “Dante”.
Citing a severe weather bulletin, Phivolcs said that Dante is expected to make landfall over Batangas province at around 5 p.m. Wednesday, and traverse western and central Luzon in the next two days.
“Due to its trajectory and potentially high-volume rainfall, Dante can be expected to generate volcanic sediment flows or lahars, muddy streamflows or muddy run-off in rivers and drainage areas on the monitored active volcanoes of Taal and Pinatubo,” Phivolcs said in an advisory.
The agency said that prolonged and intense rainfall may generate non-eruption lahars on major rivers draining the Pinatubo Volcano where significant erodible pyroclastic flow deposits of the 1991 eruption remain on the watershed.
“Pinatubo lahars will likely be channel-confined and occur on the upper to middle reaches of the Sto. Tomas- Marella and Bucao River systems but may transition to muddy streamflows and floods on the lower reaches and affect adjacent communities of San Marcelino, San Narciso, San Felipe and Botolan, Zambales Province,” it said.
“Muddy streamflows may likewise be generated along the O’Donnell and Pasig-Potrero River systems draining the Pinatubo edifice to the north and southeast, respectively, and affect downstream communities in Tarlac and Pampanga Provinces,” it added.
Moreover, Phivolcs said that continuous heavy rainfall may also result to muddy streamflow and muddy runoff around Taal Volcano, “particularly on the slopes west of Taal Lake where thin remnant ash can be remobilized in streams and roads and overland of the lakeward slopes.”
“In particular, muddy streamflow and runoff can recur on previously affected communities of Agoncillo and Laurel, Batangas Province,” the agency said.
Phivolcs has urged the communities and local government units of areas surrounding the two active volcanoes to continually monitor the weather conditions and take pre-emptive measures for their safety.