More lava flows and collapsed debris from the Mayon Volcano's ongoing "non-explosive" eruption have cascaded down the summit crater for a distance of 1.5 and 3.3 kilometers, respectively, said the Philippine Institute of Volcanology and Seismology (Phivolcs) on Sunday, June 18.

The "very slow effusion of lava" from Mayon Volcano's summit crater continued to feed lava flows and collapse debris on the Mi-isi and Bonga gullies on the volcano's south and southeastern sides, respectively, according to Phivolcs’ bulletin issued at 8 a.m.

“The lava flows have advanced to maximum lengths of 1,500 meters from the summit crater, while collapse debris have deposited to 3,300 meters from the crater,” it said.

Science and Technology Secretary Renato Solidum described the current activity of the Mayon Volcano as a “non-explosive eruption characterized by gentle release of lava from the crater.”

The restive Mayon Volcano spews steam-laden plumes visible from Sumlang Lake in Camalig and Legazpi City Albay on June 16, 2023. (ALI VICOY/MANILA BULLETIN)

Pyroclastic flows, rockfalls, volcanic quakes

In the past 24 hours, Phivolcs recorded 11 dome-collapse pyroclastic density currents (PDC) that lasted two to six minutes, 274 rockfall events, and three volcanic earthquakes.

“Continuous moderate degassing from the summit crater produced steam-laden plumes that rose 100 meters before drifting to the general west,” it added.

Phivolcs said Mayon Volcano’s sulfur dioxide emission averaged 1,004 tons per day when it was last measured on June 17.

“Short-term observations from EDM and electronic tiltmeter monitoring show the upper slopes to be inflating since February 2023,” it said

“Longer-term ground deformation parameters based on EDM, precise leveling, continuous GPS, and electronic tilt monitoring indicate that Mayon is still inflated, especially on the northwest and southeast,” it added.

Alert level 3

Mayon Volcano has been on alert level 3 since June 8, indicating that a “hazardous eruption is possible within weeks or even days.”

It is "currently in a relatively high level of unrest as magma is at the crater,” Phivolcs pointed out.

The evacuation of residents within the six-kilometer permanent danger zone has been recommended due to the risk of PDCs, lava flows, rockfalls, and other volcanic hazards.

Phivolcs warned the public to be cautious of PDCs, lahars, and sediment-laden stream flows along channels draining the volcano edifice.

It pointed out that heavy rainfall could cause channel-confined lahars and sediment-laden stream flows on channels where PDC deposits were emplaced.

Likewise, it said that ash fall events may “most likely” occur on the south side of the volcano, based on the current wind pattern.

Phivolcs advised civil aviation authorities to ask pilots to avoid flying close to the volcano because ash from sudden eruption may pose hazards to aircraft.