By ALEXANDRIA DENNISE SAN JUAN***
With typhoon “Rolly” which is now nearing super typhoon category expected to dump torrential heavy rains in Luzon, communities around Mayon Volcano, Mount Pinatubo, and Taal Volcano are facing the threat of lahar.
The Philippine Institute of Volcanology and Seismology warned residents, especially those in pre-determined zones of lahar and related hazards, to increase their vigilance and take precautionary actions against the possible phenomenon.
“Due to its trajectory, current severe intensity, and potentially high-volume rainfall, Rolly can be expected to generate volcanic sediment flows or lahar, muddy streamflows, or muddy runoff in rivers and drainage areas on the monitored active volcanoes of Mayon, Pinatubo, and Taal,” Phivolcs said in an advisory.
State volcanologists said prolonged and heavy rainfall could generate post-eruption lahar from Mayon Volcano in Albay to flow to the watershed areas of the Miisi, Mabinit, Buyuan, and Basud Channels. Mayon lahar may threaten communities downstream of these channels in Albay – Miisi, Binaan, Anoling, Quirangay, Maninila, Masarawag, Muladbucad, Nasisi, Mabinit, Matan-ag, and Basud Channels.
For Pinatubo, which is in the boundary of Zambales, Tarlac, and Pampanga, Phivolcs said non-eruption lahar are likely to be channel-confined and could occur in the upper to middle reaches of the Sto. Tomas-Marella and Bucao River systems.
Phivolcs said this could transition to muddy streamflows and floods on the lower reaches and affect San Marcelino, San Narciso, San Felipe, and Botolan in Zambales. Muddy streamflows could also 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 arlac and Pampanga.
As Rolly moves near Luzon landmass, it could also trigger lahar around Taal Volcano in Batangas, 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. Phivolcs said muddy streamflow and runoff may recur in previously affected communities in Agoncillo and Laurel in Batangas.
