Mayon Volcano’s largest recorded pyroclastic density current (PDC) since its January 6 magmatic eruption affected 32 barangays in Albay, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported Tuesday.

In an update posted at 2:15 a.m. on PHIVOLCS’ Facebook page, the agency said a 1,000-meter ash plume from Monday’s PDC traveled about four kilometers from the crater along the Mi-isi Gully. The density current, locally called an “uson,” lasted seven minutes and disturbed residents in Camalig and Guinobatan towns.

Ashfall was first reported to PHIVOLCS’ Quick Response Team by residents in Tumpa, Guinobatan, early Monday morning. The PDC resulted from a lava collapse at the start of the day, and from 10:35 a.m. to 11:37 a.m., the agency recorded a total of 12 successive PDCs.

PHIVOLCS listed the affected barangays as follows:

Camalig: Sua, Cabangan, Tumpa, Barangays 1–7, Quirangay, Sumlang, Ligban, Libod, Bariw, Salugan, Anoling, Gapo
Guinobatan: Travesia, Sinungtan, Maninila, Quitago, Ilawod, Inamnan Pequeño, Lower Binogsacan, Doña Mercedes, Malipo, Poblacion, Quibongbongan, Tandarora, San Rafael, Masarawag

The agency maintained Mayon at Alert Level 3, noting that effusive eruptions are still ongoing on the volcano’s southern and eastern slopes. Residents within an eight-kilometer radius were urged to remain alert and ready to evacuate should monitoring parameters prompt an Alert Level 4, which signals a hazardous eruption could occur within days.