MANILA, Philippines — Authorities are warning communities near Mount Pinatubo and Taal Volcano to remain on high alert as continued southwest monsoon rains could trigger lahars, muddy runoff and volcanic debris flows in parts of Luzon.
The warning was issued by the Department of Science and Technology-Philippine Institute of Volcanology and Seismology (DOST-PHIVOLCS) on Saturday, August 29, following a heavy rainfall warning from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).
PHIVOLCS said prolonged and intense rainfall could remobilize loose volcanic material deposited around the two volcanoes, creating dangerous muddy flows in rivers, drainage channels, roads and nearby communities.
At Mount Pinatubo, significant deposits left by the volcano's 1991 eruption remain in watersheds and could be washed downstream by heavy rains.
Lahars are expected to be mostly confined to river channels in the upper and middle reaches of the Sto. Tomas-Marella and Bucao river systems before potentially becoming muddy streamflows and flooding in lower areas.
Communities that could be affected include San Marcelino, San Narciso, San Felipe and Botolan in Zambales.
PHIVOLCS also warned of possible muddy streamflows along the O'Donnell and Pasig-Potrero river systems, which drain toward communities in Tarlac and Pampanga.
Taal also at risk
Taal Volcano could also experience muddy streamflows, runoff and volcanic debris flows as rainfall continues.
PHIVOLCS said old and loose volcanic deposits around Taal Lake have already become saturated from previous rains and could be remobilized by additional heavy rainfall.
The slopes west and north of Taal Lake are considered particularly vulnerable.
Communities in Agoncillo, Laurel and Talisay in Batangas could again experience muddy and debris flows in areas previously affected by similar hazards.
PHIVOLCS urged residents and local governments in identified risk areas to closely monitor weather conditions and take precautionary measures before dangerous flows occur.
The agency stressed that the lahars described in the advisory are rain-triggered, non-eruption lahars and do not necessarily indicate that either volcano is erupting.
Authorities are advising communities in vulnerable areas to remain vigilant as the southwest monsoon continues to bring heavy rainfall over western and central Luzon.
