The Philippine Institute of Volcanology and Seismology (Phivolcs) warned that heavy rains due to tropical storm “Dante” may trigger lahar flows in rivers and drainage areas of Mayon Volcano.

Citing the latest weather update of the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA), Phivolcs said Dante is expected to be over the coastal waters of Eastern Albay Province by Wednesday morning or early afternoon, June 2.

“Due to its trajectory and potentially heavy to at times intense rainfall, ‘Dante’ can be expected to generate volcanic sediment flows or lahars, muddy streamflows or muddy run-off in rivers and drainage areas of Mayon Volcano,” Phivolcs said in an advisory on Tuesday, June 1.

With this, the agency has advised communities in pre-determined zones of lahar and related hazards to be vigilant and prepared.

“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.

It noted that the bulk of erodible PDC deposits currently occupies the watershed areas of the Miisi, Mabinit, Buyuan and Basud Channels.

Moreover, the agency said that erodible eruption deposits on watershed areas located on the eastern and western slopes of the Mayon’s edifice "can be remobilized as non-eruption lahars by erosion of banks and channel beds."

Phivolcs warned that lahars and sediment-laden streamflows may occur along the Miisi, Binaan, Anoling, Quirangay, Maninila, Masarawag, Muladbucad, Nasisi, Mabinit, Matan-ag, and Basud, Bantayan Channels in Albay Province.

“Mayon lahars can threaten communities along the middle and lower slopes and downstream of these channels with inundation, burial and wash away,” it added.

Due to the severe weather, PAGASA has placed Albay Province under Tropical Cyclone Warning Signal No. 2.