PHIVOLCS warns of possible lahar from Mayon Volcano due to shear line

The shear line affecting Southern Luzon may result in volcanic sediment flows or lahars, muddy streamflows, or muddy run-off in rivers and drainage areas on Mayon Volcano, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) said Sunday.

PHIVOLCS issued the lahar advisory at 3:30 p.m. as the shear line weather system was seen to cause continued severe intensity and potentially high-volume rainfall over the province of Albay.

“Prolonged and heavy rainfall may generate post-eruption lahars on major channels draining Mayon Volcano by incorporating loose material from remnant pyroclastic density current (PDC) deposits from the January-March 2018 eruption,” PHIVOLCS said.

“The bulk of erodible PDC deposits occupy the watershed areas of the Miisi, Mabinit, Buyuan and Basud Channels. In addition, older and erodible eruption deposits that occupy the watershed areas on the eastern and western slopes of the edifice and can be remobilized as non-eruption lahars by erosion of banks and channel beds,” it added.

Mayon lahars, according to PHIVOLCS, can threaten communities downstream of the mentioned channels.

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

PHIVOLCS thus advised increased vigilance and readiness of communities in pre-determined zones of lahar and related hazards on these volcanoes.

Affected local government units were also asked to continuously monitor the weather conditions and take pre-emptive response measures for the community’s safety.

According to state weather bureau PAGASA on early Sunday morning, the shear line would affect Southern Luzon while the Northeast Monsoon or Amihan would be experienced by the rest of Luzon.

Specifically, the shear line would bring cloudy skies with scattered rains and thunderstorms to Metro Manila, Calabarzon, Bicol Region, Eastern Visayas, Western Visayas, Bulacan, Oriental Mindoro, Marinduque, Romblon, Negros Occidental, and Cebu. — BAP, GMA Integrated News