Rains due to shear line may trigger lahar from Mayon Volcano

The moderate to heavy rainfall over Albay province expected in the coming days may trigger lahar flow from Mayon Volcano, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) said in an advisory.

"This can generate volcanic sediment flows or lahars, muddy streamflows or muddy run-off in rivers and drainage areas on the monitored active volcano," it said.

"DOST-PHIVOLCS thus strongly recommends increased vigilance and readiness of communities in pre-determined zones of lahar and related hazards on Mayon Volcano," it added.

The shear line weather system affecting Southern Luzon is seen to cause the "continued potentially high-volume rainfall" over the Bicol Region, weather bureau PAGASA earlier said.

PHIVOLCS also said that "prolonged and heavy rainfall may also generate post-eruption lahars on major channels draining Mayon Volcano by incorporating loose material from remnant  PDC deposits from the January-March 2018 eruption."

The bulk of erodible PDC deposits occupy the watershed areas of the Miisi, Mabinit, Buyuan and Basud Channels, it added.

"Lahars can threaten communities downstream of the above channels with inundation, burial and wash away. Potential lahars and sediment-laden streamflows may occur along the Miisi, Binaan, Anoling, Quirangay, Maninila, Masarawag, Muladbucad, Nasisi, Mabinit, Matan-ag, Bulawan, Basud, and Bulawan Channels in Albay Province," PHIVOLCS warned.

It advised communities and local government units of the identified area of risk to continually monitor the weather conditions and take preemptive response measures as needed. —With JP De Leon/LDF, GMA Integrated News