The Mayon Volcano in Albay recorded 338 rockfalls in the 24 hours ending at midnight Friday, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported Saturday.
A total of 72 pyroclastic density currents (PDCs) were also recorded from midnight Thursday to midnight Friday. PDCs, locally referred to as uson, are extremely fast and hot mixtures of gas and volcanic debris that race down slopes and are more dangerous than slower-moving lava flows, volcanologists said.
Phivolcs also observed lava dome growth and lava flow effusion at the summit crater. Mayon remains under Alert Level 3, which means intensified unrest or magmatic unrest. Crater glow was visible to the naked eye, the agency added.
During the same period, the volcano emitted 4,970 tons of sulfur dioxide, while plumes were observed but partly obscured. Phivolcs warned of possible hazards, including rockfalls, landslides, lava flows, lava fountaining, PDCs, moderate explosions, and lahars during heavy and prolonged rainfall.
Entry into the six-kilometer Permanent Danger Zone and the Extended Danger Zone remains prohibited. Phivolcs also advised aircraft to avoid flying close to the volcano.
The Office of Civil Defense said heightened precautions are needed due to Mayon’s continued unrest and Tropical Storm Ada (international name: Nokaen).
Phivolcs earlier recorded increased seismic energy and volcanic gas release, with three monitoring stations showing a spike in real-time seismic amplitude measurement despite the absence of volcanic earthquakes. The agency said the increase was driven by intensified rockfall and PDC activity, indicating higher lava effusion rates at the summit.
Heavy rains from Tropical Storm Ada triggered flooding and landslides in several parts of Albay, rendering roads and bridges impassable and forcing hundreds of families to evacuate.
Daraga Mayor Victor Perete said 509 families from Barangays Budiao, Bañadero, Malobago, Matnog, and Busay were moved to safer areas due to lahar risks. Evacuations were also reported in Polangui and Guinobatan towns, while strong river currents in Manito town washed away a bamboo bridge connecting Barangays Cawit and It-ba.
The National Disaster Risk Reduction and Management Council said more than 4,500 passengers were stranded in Calabarzon, Bicol, Eastern Visayas, and Caraga.
