State volcanologists warned Monday of a “heightened likelihood” of increasing magmatic activity at Kanlaon Volcano following the observation of a visible crater glow, locally known as “banaag.”

In an advisory issued at 1:30 a.m., the Philippine Institute of Volcanology and Seismology (Phivolcs) reported that superheated volcanic gas plumes were detected emitting from the summit crater.

Personnel at the Kanlaon Volcano Observatory in Negros Occidental first observed the incandescence with the naked eye at 7 p.m. Saturday.

Volcanologists described the “banaag” phenomenon as a common precursor to a magmatic eruption at the volcano. According to the agency, superheated gas activity has become more frequent since it was first monitored in November 2024.

Phivolcs reported that seismic activity remains steady, averaging six volcano-tectonic earthquakes per day. However, sulfur dioxide emissions have shown a slight increase, averaging 2,382 metric tons per day over the past week compared to the long-term average of 1,646 metric tons.

Kanlaon Volcano remains under Alert Level 2, which signifies moderate volcanic unrest. Phivolcs officials stated the status could be raised to Alert Level 3 if signs of a magmatic eruption become more evident.

The agency reminded the public that entry into the four-kilometer radius Permanent Danger Zone is strictly prohibited due to the increased risks of sudden steam-driven or phreatic eruptions.

Civil aviation authorities have also been advised to caution pilots against flying close to the volcano’s summit.