The Philippine Institute of Volcanology and Seismology (Phivolcs) on Thursday, Jan. 1, raised the alert status of Mayon Volcano from Alert Level 1 to Alert Level 2 following a sustained increase in volcanic unrest marked by intensified rockfall activity and prolonged ground deformation.

In its Mayon Volcano Bulletin, Phivolcs said the alert level was raised due to signs that unrest at the volcano is being driven by shallow magmatic processes.

“Since November 2025, an increase in rockfall shed by the summit lava dome of Mayon Volcano has been recorded by visual and seismic monitors of the Mayon Volcano Network,” the agency stated.

Phivolcs noted that a total of 599 rockfall events were detected in the last two months of 2025, averaging 10 events per day, but activity intensified in the final week of December.

“A total of 599 rockfall events have been detected in the last two months of 2025, or an average of 10 events/day, but in the last week of December 2025, average rockfall increased to 21 events/day,” it stated.

Phivolcs added that 47 rockfall events were recorded on Dec. 31, the highest daily total observed over the past year.

According to the agency, increased rockfall activity has previously served as a precursor to eruptive episodes at Mayon.

“Increased rockfall at Mayon has been a precursory sign of magmatic dome growth within the upper edifice preceding an eruption, similar to conditions before the 2023 eruption,” it said.

While Phivolcs said no significant volcanic earthquake or sulfur dioxide anomalies have been detected, it pointed to long-term and short-term ground deformation as a key concern.

“Likewise, current unrest has exhibited no significant volcanic earthquake or sulfur dioxide anomalies, but in contrast to 2023, ground deformation parameters have been anomalous for almost 18 months.”

It noted that long-term monitoring data indicate sustained swelling of the volcano’s structure.

“Long-term ground deformation data based on EDM, continuous GPS, and electronic tilt monitoring indicate that the Mayon edifice, particularly its eastern to northeastern slopes, has been swelling or inflating since June 2024.”

Also, the agency said short-term deformation was also observed on other flanks.

Phivolcs said the combination of persistent rockfall and prolonged deformation suggests an increased likelihood of eruptive activity.

“Persistent and increasing rockfall, coupled with long- to short-term swelling of the edifice, may indicate increased chances of an eruption occurring at the summit of Mayon, generating hazardous volcanic hazards that may impact surrounding communities,” the agency said.

With the raising of Alert Level 2, Phivolcs warned that the volcano is exhibiting moderate unrest that could escalate.

“This means that there is current unrest driven by shallow magmatic processes that could lead to hazardous magmatic eruption,” it said.

The agency reiterated strict safety measures, urging the public to avoid the six-kilometer-radius Permanent Danger Zone (PDZ).

“The public is strongly advised to be vigilant and refrain from entering the six (6) kilometer-radius Permanent Danger Zone (PDZ) to minimize risks from sudden explosions, pyroclastic density currents (PDC) or uson, rockfall, landslides and ballistic projectiles,” it said.

Phivolcs likewise directed local government units to prepare for possible evacuations.

“Local government units must prepare communities within the PDC hazard zone for subsequent evacuation in case unrest suddenly escalates and the Alert Level is further raised,” it stated.

Meanwhile, Phivolcs cautioned civil aviation authorities against flights near the volcano’s summit.

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