Mayon produces 'largest' pyroclastic flow, 1000-meter ash plume

MANILA, Philippines, February 10 ------ Since showing increased activity earlier this year, Mayon Volcano generated its "largest" pyroclastic density current so far, with an ash plume reaching up to 1,000 meters yesterday, Phivolcs reported.

At around 10:35 a.m., a pyroclastic density current, locally called uson, raced down Mayon Volcano's Mi-isi Gully slope for up to 4 kilometers. On Sunday, February 8, state seismologists recorded eight volcanic earthquakes, 469 rockfall events, and 43 pyroclastic density currents. They also observed that the volcano produced a brownish ash plume 1 kilometer high above the crater, drifting southwest and triggering ashfall in Barangays Camalig and Guinobatan, Albay.

The volcano remains under Alert Level 3, indicating relatively high unrest and an elevated risk of eruption since the first week of January. The number of rockfall events and pyroclastic density currents, which are composed of hot gas and fragmented volcanic particles, has been increasing in recent weeks. On February 7 alone, Mayon Volcano experienced two volcanic earthquakes, 401 rockfall events, and 17 pyroclastic density currents.

Since then, Mayon Volcano has been emitting sulfur dioxide at the rate of 1,799 tonnes per day. The highest rate in recent weeks, however, was on February 4, when the emission rate posted 6,569 tonnes per day. The volcano recorded one of its highest levels of activity in late January, producing hundreds of volcanic earthquakes and numerous rockfall events.

Seismic activity included a tremor that lasted nearly two days, with pyroclastic density currents exceeding those observed on Sunday. The heightened activity was driven by the combined effusion of the lava dome and lava flows, along with low-level, intermittent volcanic explosions.

Lava effusion has been occurring at the volcano for 34 days already. While it is not the first time a pyroclastic density current has generated a 1,000-meter ash plume, such events have been rare over the past six weeks. Phivolcs urged communities near Mayon Volcano to stay clear of the 6-kilometer-radius permanent danger zone, as multiple hazards continue, including rockfalls, landslides, ballistic fragments, lava flows and fountaining, pyroclastic density currents, moderate explosions, and lahars during heavy or prolonged rainfall.

Source: philstar.com