Mount Mayon in Albay spewed ash again on Monday morning.
The Philippine Institute of Volcanology and Seismology, in a bulletin issued 10:15 am on Monday, said two phreatic eruptions were observed between 7:59 am and 8:05 am.
Mayon Volcano has been under Alert Level 2 since late March this year, meaning “a moderate level of unrest.”
A phreatic eruption is steam-driven and occurs when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits, Phivolcs said in a statement.
The eruptions generated grayish to grayish white ash plume that rose 300 to 500 meters above the summit before drifting southwest, the agency added.
Sudden explosions, lava collapses, pyroclastic density currents, and ashfall can still occur and threaten areas in the upper to middle slopes of Mayon, Phivolcs said.
People should not be allowed to enter the 6-kilometer-radius permanent danger zone and the 7-kilometer-radius extended danger zone stretching from Anoling, Camalig, to Sta Misericordia, Sto Domingo in Albay, it added.
People residing close to these danger areas are also advised to observe precautions associated with rockfalls, PDCs, and ashfall, Phivolcs said. Aircraft must also avoid flying close to Mayon’s summit.
In January, the volcano was placed under Alert Level 4, which meant a “hazardous” eruption was possible. This was lowered to Alert Level 3, and then to Alert Level 2, in March.
More than 54,600 evacuees from around the mountain were also allowed to go home.