Mayon Volcano alert lowered to Alert Level 2

The Philippine Institute of Volcanology and Seismology (Phivolcs) on Wednesday downgraded Mayon Volcano's alert status from Alert Level 3 (magmatic unrest / increased tendency towards hazardous eruption) to Alert Level 2 (moderate level of unrest).

In its bulletin, Phivolcs said the lowering of Mayon's alert level was based on monitoring network and observation of day-to-day conditions that recorded a general decline in unrest since July 23, as indicated by different monitored parameters.

On the activity at the summit crater, eruptive activity at Mayon’s summit crater has declined based on the decreasing record of Strombolian events, lava effusion, and lava collapse-fed rockfall and pyroclastic density currents (PDCs).

The downslope advance of active lava flows on the Mi-isi, Bonga, and Basud Gullies halted at respective radial distances of 2.7 km., 3.2 km., and 3.8 km. from the summit crater on July 22, indicating a cessation of supply of fresh magma from the crater in this period.

The lava collapse-fed rockfall decreased from an average of 278 events/day from the start of eruption on Jan. 6, to 12 events/day from July 23, as lava flows began stabilizing in place and shedding less and less material onto the volcano slopes.

Discrete Strombolian and PDC activity have ceased after the last recorded events on July 26 and 28.

Phivolcs said the volume of erupted lava, including rockfall and PDC deposits, totals approximately 89 million cubic meters.

On the seismic activity, the volcanic earthquakes generated by Strombolian activity, magma extrusion, degassing and occasional rock-fracturing beneath the edifice have diminished from a monthly average of 57 events/day to 13 events/day.

“Real-time seismic energy release from the volcano or RSAM has also returned to pre-eruption levels. These seismic parameters are consistent with the observed decline in surface (lava flow, lava collapse-fed rockfall and PDC) activity and likewise reflect the cessation of magma supply to the summit crater,” it said.

On the other hand, volcanic sulfur gas (SO2) emission obtained peaked at a record average of 13,128 tonnes/day on June 11 prior to the onset of peak Strombolian activity, but has decreased since.

The SO2 emission from the onset of eruption averages 2,450 tonnes/day, while emission since July 23 (after the cessation of magma supply) averages 2,163 tonnes/day.

The decreased but sustained levels of volcanic degassing indicate that while magma supply to the summit crater may have ceased, batches of magma continue to be periodically intruded in storage beneath the edifice, consistent with ground deformation and microgravity data.

In its ground deformation and microgravity, long-term ground deformation data from Global Positioning System (GPS), Electronic Distance Measurements (EDM), and electronic tilt measurements indicate that the volcanic edifice has remained generally asymmetrically inflated since January 2025.

The overall ground deformation and microgravity parameters suggest that while the edifice has been depressurized due to shallow magmatic eruption processes, the Mayon edifice remains generally pressurized with respect to background conditions.

Phivolcs, however, said the lowering of the alert status should not be interpreted to mean that the volcano’s unrest has ceased, considering that the edifice is still pressurized and SO2 emission remains high relative to baseline levels.

“The public is strongly advised to be vigilant and refrain from entering the 6-km.-radius Permanent Danger Zone (PDZ) to minimize risks from sudden minor explosions or phreatic eruptions that could generate volcanic hazards, such as short-range PDCs, rockfall, ballistic projectiles, and landslides. Thin ashfall could also be experienced downwind of the Mayon edifice in the event of minor explosions, phreatic eruptions, or lava collapse-fed PDCs,” Phivolcs said.

It added that given the large amounts of volcanic material deposited by the 2026 eruption, heavy to intense rainfall could generate post-eruption lahars and sediment-laden streamflow in channels draining the Mi-isi, Bonga, and Basud Gullies.

Communities and local government units along these lahar channels, as well as along channels of perennial lahar hazards, must be vigilant and ready to evacuate in the event of heavy or intense rainfall on the volcano slopes that could potentially generate life-threatening lahars and sediment-laden streamflow.

Civil aviation authorities must also advise pilots to avoid flying near the volcano’s summit as ash from any sudden eruption can be hazardous to aircraft.

-Connie Calipay/Philippine News Agency