Phivolcs lowers Mayon alert level

LEGAZPI CITY, Albay: After several months of unrest in the Mayon Volcano, the Philippine Institute of Volcanology and Seismology (Phivolcs) lowered the alert level over the volcano on Thursday, March 16.

In a bulletin released by Phivolcs, the alert status of Mayon was brought down to Alert Level 2 (moderate level of unrest) to Alert Level 1 (low level of unrest).

The lower alert level means the likelihood of an eruption occurring within the immediate future has diminished.

Since the first week of December 2022, volcanic earthquakes recorded by the Mayon Volcano Network have declined to an average of 0-1 event per day.

Most of these occurred at depths of 6-10 kilometers beneath the eastern flanks and were attributed to rock fracturing processes within the volcano.

Rockfall from Mayon’s summit dome also occurred during periods of intense rainfall over the summit area, rather than from extrusion of new dome lava at the crater.

Ground deformation results showed that the volcano edifice has been deflating since July- August 2022.

Longer-term data suggested that the current ground deformation behavior of Mayon is largely driven by tectonic processes (e.g. earthquake activity in the Bicol Region) rather than pressurization from volcanic sources.

Sulfur dioxide emission flux from the crater based on continuous gas spectrometry varied between a high 477 tons per day on Dec, 8, 2022, and a low of 201 tons per day on March 2, 2023.

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.

The public is still reminded to avoid entry into the 6-km permanent danger zone or PDZ because of perennial hazards from rockfall, avalanche, ash puff and sudden steam-driven or phreatic eruption at the summit area.

Phivolcs told civil aviation authorities to advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft.

Furthermore, people living in valleys and active river channels are cautioned to remain vigilant against sediment-laden streamflows and lahars in the event of prolonged and heavy rainfall brought about by the advent of the rainy season.