Mayon is now under Alert Level 2 --- Phivolcs

The Philippine Institute of Volcanology and Seismology (Phivolcs) on Friday, Dec. 8, announced the lowering of Mayon Volcano’s status from Alert Level 3 or decreased tendency towards hazardous eruption to Alert Level 2 or moderate level of unrest.

In an advisory, Phivolcs cited Mayon Volcano’s monitoring network and observation of day-to-day conditions have recorded a “general decline in unrest” since November 2023.

Phivolcs monitoring showed that volcanic earthquakes generated by magma extrusion and degassing and occasional rock-fracturing beneath the edifice have “decreased” --- from a monthly average of 11 events/day in November 2023 to nearly zero events/day in the first week of December 2023.

Moreover, Phivolcs said that the recorded rockfall and pyroclastic density currents or PDCs also “significantly decreased” --- from monthly averages of 122 to 87 events/day and 5 to 2 events/day, respectively --- between October and November 2023 to virtually 0 event/day in the first week of December 2023.

“These decreases indicate that magma supply to the summit crater has significantly diminished, resulting in the cessation of lava effusion from the crater and lava collapse-driven rockfall and PDC activity,” Phivolcs said.

Additionally, Phivolcs also observed “lessening incandescence” of the summit crater and the 2023 lava flow deposits since the last week of November 2023.

“The stabilization and diminishing incandescence of lava deposits at the summit and depositional gullies are consistent with the cessation of magma supply to the summit crater,” Phivolcs noted.

However, Phivolcs observed the “asymmetric deformation” of the Mayon edifice throughout its period of unrest that persists.

“Overall, ground deformation and microgravity parameters indicate that pressurization of the Mayon edifice has abated in the past month, but that the edifice remains generally pressurized (inflated) due to magma intrusion that has been transpiring since the onset of unrest in June 2023,” Phivolcs said.

Phivolcs noted that Volcanic SO2 emission has also been “decreasing and increasing” in cycles of generally lessened peaks. 
“The overall weakening of cyclic SO2 emission indicates that volcanic gas from lava exposed on the crater and slopes of Mayon and from magma stored within the volcano is diminishing, but that minor volumes of magma are still periodically intruded in storage beneath the edifice, consistent with ground deformation and microgravity data,” Phivolcs added.

Public caution

While the Mayon’s status has been downgraded, Phivolcs stressed that 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 inflated and SO2 emission remains high relative to baseline levels.”

Given this, the public was strongly advised to be “vigilant and desist” from entering the six (6) kilometer-radius Permanent Danger Zone (PDZ) to minimize risks from explosions, rockfalls, and landslides.

Civil aviation authorities were also asked to advise pilots to “avoid flying close” to the volcano’s summit as ash from any sudden eruption can be hazardous to aircraft.