LEGAZPI CITY, Albay – Authorities in this province have started the pre-emptive evacuation of thousands of families as typhoon “Opong” is expected to bring heavy to intense rains that may trigger flooding and dangerous lahar flows from Mayon Volcano.

The Albay Public Safety and Emergency Management Office (APSEMO) said 107,763 families or 491,973 individuals are at risk of flooding while another 55,752 families or 210,843 individuals are threatened by possible lahar flows.

Roderick Mendoza, officer-in-charge of APSEMO, said the evacuation began early Wednesday morning and is expected to be completed by 4 p.m. that day.

He said that the figures were based on APSEMO’s February 2024 assessment of families vulnerable to lahar and flooding while the final count of evacuees will be determined later.

As part of the preparation, classes in public and private schools across the province have shifted to alternative learning modes and were fully suspended starting Sept. 25 until further notice.

Government work in Albay was suspended beginning 12 noon, Sept. 25, except for offices involved in public safety, disaster response, health, and related services while private companies may decide at their discretion.

Authorities prohibited river crossings, fishing, and swimming until floodwaters recede.

All mass gatherings, outdoor activities, educational tours, and related permits have also been revoked.

The Philippine Institute of Volcanology and Seismology (Phivolcs) issued a lahar advisory on Wednesday evening, warning that heavy rainfall from Opong could mobilize volcanic debris around Mayon Volcano.

Phivolcs noted that loose pyroclastic deposits from the 2018 and 2023 eruptions remain in the Miisi, Mabinit, Buyuan, and Basud channels, making them highly susceptible to erosion. Older deposits on the eastern and western slopes may also be remobilized, increasing the risk of lahar.

Communities downstream of these channels – Miisi, Binaan, Anoling, Quirangay, Maninila, Masarawag, Muladbucad, Nasisi, Mabinit, Matanag, Basud, and Bulawan – are at risk of inundation, burial, and possible washout.

Phivolcs urged residents and local government units to maintain vigilance, monitor rainfall, and carry out pre-emptive safety measures.

The Office of Civil Defense (OCD) in Bicol placed the region under red alert status starting Sept. 24.

Disaster councils were instructed to pre-position relief goods, prepare evacuation facilities, and keep disaster operation centers open 24/7.

As of Wednesday, OCD reported 2,146 individuals stranded in different ports across Bicol, along with 868 rolling cargoes and four vessels unable to travel due to rough seas.

Authorities emphasized that strict compliance with preparedness protocols is essential to protect lives and property as Opong moves closer to the Bicol region.