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Mayon Volcano alert status down to ‘Level 1’ —PHIVOLCS

The alert level status of Mayon Volcano in Albay has been deescalated to "Level 1," or "low level of unrest," the Philippine Institute of Volcanology and Seismology (PHIVOLCS) said Thursday.

Under Alert Level 1, PHIVOLCS said the likelihood of an eruption occurring within the immediate future has diminished.

PHIVOLCS said that Mayon Volcano has shown a “steady decline” in its monitored parameters since the start of the year. Among these is the decline in Mayon’s recorded volcanic earthquakes to an average of 0–1 event per day since the first week of December 2022.

“Most of these occurred at depths of 6–10 kilometers beneath the eastern flanks and are attributed to rock fracturing processes within the volcano. In addition, rockfall from Mayon’s summit dome occurred during periods of intense rainfall over the summit area, rather than from extrusion of new dome lava at the crater,” PHIVOLCS said.

Results from the precise leveling campaign also indicated that Mayon’s edifice has been continuously deflating since July to August 2022.

PHIVOLCS said a localized short-term inflation of the middle to upper southeastern slopes was recorded by several technologies since early February 2023, but longer-term data suggest that the current ground deformation behavior of Mayon is largely driven by tectonic processes rather than pressurization from volcanic sources.

Mayon’s sulfur dioxide (SO2) emission also varied between 477 tonnes per day on December 8, 2022, to 201 tonnes per day on March 2, 2023.

“These SO2 emissions are considerably below the background level of 500 tonnes/day, and such relatively low levels are consistent with passive degassing of resting magma beneath the edifice,” PHIVOLCS added.

Additionally, Mayon’s summit crater only spewed weak to moderate degassing plumes since the beginning of 2022.

“The summit lava dome, which grew a total extruded volume of 132,000 m3 between June and December 2022, has not exhibited further growth since. Crater glow, or incandescence associated with superheated gas emitted from the summit crater, has remained weak and visible only with the aid of a telescope. These observations of stable summit conditions are consistent with the absence of magma re-supply to the shallow levels of the edifice,” PHIVOLCS said.

Even as Mayon Volcano is now on Alert Level 1, PHIVOLCS still reminded the public to avoid entry into the 6-kilometer Permanent Danger Zone due to perennial hazards of rockfall, avalanche, ash puff, and sudden steam-driven or phreatic eruption at the summit area.

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

People living in valleys and active river channels were likewise cautioned to remain vigilant against sediment-laden stream flows and lahars in the event of prolonged and heavy rainfall. —VAL, GMA Integrated News