Mayon Volcano emits pyroclastic density current along Mi-isi gully

MANILA, Philippines — A pyroclastic density current (PDC), locally known as “uson,” was observed at Mayon Volcano on Saturday, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).

Phivolcs, in an initial advisory, said an ongoing PDC was seen moving along the Mi-isi gully on the volcano’s south-southwestern slopes.

Pyroclastic density currents are fast-moving flows of hot volcanic gas, ash and rock fragments that descend the slopes of a volcano during an eruptive activity.

“Current details of the ongoing event: Plume drift is currently going west-southwestward. Estimated PDC run-out is four kilometers,” Phivolcs said in an update.

Based on Phivolcs’ latest 24-hour monitoring, Mayon Volcano remains under Alert Level 3, indicating intensified or magmatic unrest.

The agency reported ongoing lava effusion with lava flows extending along the Basud gully, Bonga gully and the Mi-isi gully.

Episodic minor eruptions and short-lived lava fountaining were also observed.

Phivolcs also recorded 39 volcanic earthquakes, including 21 volcanic tremor events lasting from one to 44 minutes, as well as 376 rockfall events in the last 24-hours.

Meanwhile, sulfur dioxide flux averaged 2,147 tons per day on May 1, while moderate plume emission reached 200 meters above the crater with west-southwest, west-northwest and west drifts.

Under Alert Level 3, entry into the 6-kilometer radius permanent danger zone is prohibited. /apl