Authorities raised the alert status of Mayon Volcano on Thursday following a sharp increase in rockfalls and signs of internal pressure that indicate a growing possibility of an eruption.

The Philippine Institute of Volcanology and Seismology (Phivolcs) moved Mayon to Alert Level 2, signifying “moderate unrest.” The agency warned that the persistent rockfalls and the “swelling” of the volcano’s edifice suggest magma may be rising toward the surface.

Under Alert Level 2, the public is strictly prohibited from entering the six-kilometer Permanent Danger Zone. Potential hazards include sudden explosions, rockfalls, landslides, and pyroclastic density currents — rapidly moving clouds of hot gas and volcanic debris.

Monitoring stations recorded 599 rockfall events since November, but the frequency intensified significantly in late December. On New Year’s Eve, 47 rockfalls were recorded in a single day, up from an average of 10 per day earlier in the month.

“Increased rockfall at Mayon has been a precursory sign of magmatic dome growth,” Phivolcs said in a statement, noting the current conditions mirror those seen before the volcano’s 2023 eruption.

While the agency has not yet detected significant volcanic earthquakes or unusual sulfur dioxide emissions, ground deformation data shows the volcano’s slopes have been inflating since mid-2024.

Aviation officials have been advised to warn pilots against flying near the summit, as ash and ballistic fragments could endanger aircraft.