MANILA — The Philippine Institute of Volcanology and Seismology (Phivolcs) warned Friday that Typhoon Rolly’s expected heavy rainfall could cause lahar flows in rivers and drainage areas near 3 volcanoes in Luzon, and urged residents near the areas to be prepared.
Communities near Mayon, Pinatubo, and Taal volcanoes must increase their vigilance and must take necessary precautions amid Typhoon Rolly’s intense rains, Phivolcs said.
“Due to its trajectory, current severe intensity and potentially high-volume rainfall, Rolly can be expected to generate volcanic sediment flows or lahars, muddy stream flows or muddy run-off in rivers and drainage areas on the monitored active volcanoes,” state seismologists said.
Potential lahar flows from the Mayon volcano, Phivolcs said, may occur along Miisi, Binaan, Anoling, Quirangay, Maninila, Masarawag, Muladbucad, Nasisi, Mabinit, Matan-ag, and Basud Channels in Albay Province.
“Mayon lahars can threaten communities downstream of the above channels with inundation, burial and wash away,” it said.
Mt. Pinatubo’s lahars, meanwhile, are likely to be “channel-confined” and may occur on the upper to middle reaches of the Sto. Tomas-Marella and Bucao River systems.
According to Phivolcs, the muddy stream flows from Mt. Pinatubo could affect communities in San Marcelino, San Narciso, San Felipe and Botolan in Zambales.
“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,” said Phivolcs.
Typhoon Rolly, which is nearing the strength of a super typhoon category, could also trigger lahar flow around Taal Volcano, it added.
It could recur on previously affected communities of Agoncillo and Laurel in Batangas.
“Prolonged and heavy rainfall may generate 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.”
Typhoon Rolly on Friday night continued to intensify into near the super typhoon category as it barreled closer to eastern Luzon, state weather bureau PAGASA said.
The Japan Meteorological Agency has categorized Rolly as a "violent typhoon," the highest category.