LEGAZPI CITY – The Philippine Institute of Volcanology and Seismology (Phivolcs) on Friday lowered Mt. Mayon's alert status from Level 3 to 2 due to declining parameters in volcanic activities.
Level 3 means a hazardous eruption is possible while Level 2 signifies moderate unrest.
In its Dec. 8 bulletin, Phivolcs said the lowering of the alert level was supported by different parameters and observations.
Seismic activities have declined from a monthly average of 11 volcanic earthquakes in November to zero in the first week of December. Volcanic earthquakes are typically attributed to rock fracturing beneath the edifice and occasional rockfall.
The overall low-level seismicity signifies that the magma supply to the summit crate has significantly reduced.
On the other hand, the sulfur gas (SO2) output has decreased from an average of 4,756 tonnes/day on Aug. 16 to 859 tonnes/day on Dec. 7.
The overall low level of SO2 gas emission indicates that the volcanic gas from lava exposed on the crater and slopes of Mayon and from magma stored within the volcano is declining.
Visual observation of the summit recorded lessening incandescence of the summit crater and the 2023 lava flow deposits since the last week of November.
In its ground deformation, data from continuous global positioning system (GPS) and electronic distance meter (EDM) measurements and radial tilt indicated asymmetric deformation of the Mayon edifice throughout its period of unrest.
Phivolcs, however, reminded the public that lowering the alert status should not be interpreted as the end of the volcano's unrest.
"Considering that the edifice is still inflated and SO2 emission remains high relative to baseline levels. The public is strongly advised to be vigilant and to avoid entry into the 6-km Permanent Danger Zone (PDZ) to minimize risks from explosions, rockfalls and landslides,” the bulletin said.
Mayon Volcano’s alert level was raised to 3 in June this year, prompting the local government units to evacuate 5,672 families in Camalig, Daraga, Guinobatan, Ligao City, Tabaco City, Malilipot, and Sto. Domingo.
OCD downgrades alert level in Bicol
Meanwhile, the Office of Civil Defense downgraded the alert status of its emergency operations center in the Bicol Region from "blue" to "red".
A "blue" alert status in the agency means half of its manpower is on standby for heightened monitoring on the matter.
The OCD will decamp 52 families or 195 individuals inside an evacuation center funded by the National Disaster Risk Reduction and Management Council in Camalig town.
The agency is coordinating with local officials in Camalig regarding the decamping.
Even with the lowering of the volcano's status, the OCD advised local disaster risk reduction management offices to continue monitoring the volcano and other hazards that could impact nearby communities. (With report from Priam F. Nepomuceno/PNA)