A brief episode of incandescent lava fountaining was observed at Mayon Volcano early Tuesday, Jan. 13, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

Phivolcs reported that the lava fountain, which reached an estimated height of around 100 meters, occurred at 1:39 a.m. at the summit crater and lasted for about 35 seconds.

Alert Level 3 remains hoisted over Mayon due to intensified magmatic unrest, Phivolcs said.

From 12 a.m. of Jan. 12 to 12 a.m. of Jan. 13, continued lava dome and lava flow effusion were observed.

The volcano also generated 206 rockfall events and 63 pyroclastic density currents, locally known as “uson.”

Phivolcs said a fair crater glow was visible to the naked eye during observation periods.

It added that sulfur dioxide emissions were measured at 526 tons on Jan. 11.

Volcanic plumes rose to about one kilometer above the crater, showed moderate emission, and drifted toward the west-southwest and southwest.

Phivolcs reiterated that entry into the six-kilometer-radius permanent danger zone and entry without vigilance into the extended danger zone remain prohibited.

Flying aircraft close to the volcano is likewise not allowed because of possible hazards from ash and other volcanic debris.

The agency reminded the public and local authorities of the dangers that may occur while Alert Level 3 remains in effect, including rockfalls, landslides or avalanches, ballistic fragments, lava flows and lava fountaining, pyroclastic density currents, moderate-sized explosions, and lahars during heavy and prolonged rainfall.