State volcanologists warned of possible lahar flow from Mayon Volcano caused by the expected heavy rainfall caused by the shear line weather system affecting the southern portion of Luzon on Friday, February 21, 2025.

“Based on the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) Weather Advisory No. 10 issued at 11:00AM today, 21 February, 2025, a “shear line” weather system affecting Southern Luzon is predicted to cause continued potentially high-volume rainfall over Bicol Region. Heavy to intense rainfall is expected over the Albay Province in the coming days,” according to the advisory by the Philippine Institute of Volcanology and Seismology (PHIVOLCS) in a report on GMA News Online.

“This can generate volcanic sediment flows or lahars, muddy streamflows or muddy run-off in rivers and drainage areas on the monitored active volcano,” the agency added, noting that nearby communities must prepare for possible hazards.

PHIVOLCS also pointed out that the prolonged and heavy rainfalls could generate post-eruption lahars on major channels draining the volcano “by incorporating loose material from remnant PDC (pyroclastic density currents) deposits from the January-March 2018 and June-December 2023 eruptions.”

“The bulk of erodible PDC deposits occupy the watershed areas of the Mi-isi, Mabinit, Buyuan, Bonga and Basud Channels,” the state volcanologists said.

Potential lahars and sediment-laden streamflows may occur along the Miisi, Binaan, Anoling, Quirangay, Maninila, Masarawag, Muladbucad, Nasisi, Mabinit, Matan-ag, Buyuan, Basud, and Bulawan Channels in Albay Province, the PHIVOLCS noted.

The state weather bureau PAGASA said earlier in the day that the Visayas, MIMAROPA, Bicol Region, Northern Mindanao, Caraga, Zamboanga Peninsula, Quezon, and Davao Oriental will have cloudy skies with scattered rains and isolated thunderstorms due to the shear line with flash floods or landslides possibly occurring due to moderate to heavy rains. 

(with reports from Vince Angelo Ferreras/RSJ, GMA Integrated News)