Kanlaon exhibits first visible crater glow; Alert Level 3 escalation looms

MANILA, May 11 ------ The Philippine Institute of Volcanology and Seismology (Phivolcs) has raised the alarm over a "new development" at Kanlaon Volcano after state volcanologists and local residents observed a visible crater glow, or banaag, for the first time on Sunday evening.

In a bulletin issued at 1:30 a.m. on Monday, May 11, the agency reported that the incandescence at the summit was spotted by the naked eye at approximately 7:00 p.m. on May 10. The glow is caused by superheated volcanic gases—a phenomenon that has been detected by infra-red cameras since late 2024 but has only now become visible to the public.

Phivolcs noted that while crater glow is a common precursor to magmatic eruptions at Mayon Volcano, its appearance at Kanlaon signals a potential shift in the volcano's behavior. "If crater glow becomes sustained and intensifies, this would indicate that magma is close to or at the crater," the agency warned. Such intensification could lead to a full-scale magmatic eruption within a matter of days.

Despite this visual development, other monitoring parameters have remained relatively stable since the volcano's last moderate explosive eruption on March 15, 2026. "Since then, seismicity remained at the steady rate of six (6) volcano-tectonic earthquakes/day, while sulfur dioxide ($SO_2$) gas emissions based on campaign mDOAS measurements averaged 1,646 tonnes/day and have increased only slightly to 2,382 tonnes/day this past week," the bulletin stated. "Ground deformation parameters have been non-steady but still indicate a sustained and slow-rate inflation of the volcano edifice since 2022," the agency added.

Kanlaon remains under Alert Level 2 (Increasing Unrest). However, authorities emphasized that the status could be escalated to Alert Level 3 should the crater glow intensify. A magmatic eruption poses several life-threatening hazards, most notably Pyroclastic Density Currents (PDCs), also known locally as uson—fast-moving, lethal clouds of hot gas and volcanic debris. Other risks include lava flows, ballistic volcanic rocks, and heavy ashfall. With its 24-hour monitoring ongoing, Phivolcs has reiterated its recommendation to LGUs for the strict evacuation of all communities within the 4-kilometer radius Permanent Danger Zone (PDZ). Residents along river channels are urged to remain vigilant against the threat of lahars during intense rains. A "no-fly" warning also remains in effect near the summit to avoid catastrophic aircraft engine failure from sudden ashfall.

Source: news.abs-cbn.com