The Philippine Institute of Volcanology and Seismology (Phivolcs) on Monday, June 5 raised the alert level of Mayon Volcano in Albay from level 1 to 2 due to “increasing unrest.”

In its bulletin issued at 10 a.m., Phivolcs said Mayon Volcano is showing “unrest driven by shallow magmatic processes that could eventually lead to phreatic eruptions or even precede hazardous magmatic eruption.”

“The public is strongly advised to be vigilant and desist from entering the six kilometer-radius permanent danger zone to minimize risks from sudden explosions, rockfall and landslides. In case of ash fall events that may affect communities downwind of Mayon’s crater, people should cover their nose and mouth with a damp, clean cloth or dust mask,” it said.

(Screengrab from Phivolcs)

It noted that the daily visual and camera monitoring of the summit crater revealed an increase in rockfall from the Mayon Volcano’s summit lava dome since the last week of April 2023, which indicates “aseismic” growth.

Phivolcs said that rockfall increased in frequency from an average of five events per day to 49 events per day in the past 24 hours.

“A total of 318 rockfall events have been recorded by the Mayon Volcano Network since April 1, 2023, while 26 volcanic earthquakes have been recorded for the same period,” it pointed out.

Phivolcs said that as of May 9, 2023, the “lava dome has increased in volume by approximately 83,000 cubic meters since Feb. 3, 2023 and a total of nearly 164,000 cubic meters since Aug. 20, 2022.”

“Short-term observations from EDM and electronic tiltmeter monitoring show the upper slopes to be inflating since February 2023. Longer-term ground deformation parameters based on EDM, precise leveling, continuous GPS, and electronic tilt monitoring indicate that Mayon is still inflated, especially on the northwest and southeast, since 2020,” it added.

Moreover, Phivolcs recorded the highest sulfur dioxide emission on April 29, averaging 576 tons per day, and the last measurement on May 23, averaging 162 tons per day.

“These low-level volcanic earthquakes, ground deformation, and volcanic gas parameters are overshadowed by recent steep increases in rockfall events which may possibly lead to further dome activity,” it said.