Late on the night of May 9, 2026, staff at the Kanlaon Volcano Observatory in Canlaon City pointed a DSLR camera at the summit and captured something they had not seen during the current period of unrest: a bright glow rising from the crater. The Philippine Institute of Volcanology and Seismology, known as PHIVOLCS, recorded the phenomenon at 11:40 p.m. and again at 7:03 p.m. on May 10, when the glow became visible to the naked eye for the first time. The agency has warned that another eruption in the coming days could push the alert status to Level 3, a threshold that signals the potential for a fully magmatic eruption capable of producing deadly pyroclastic flows and lahars.
For the roughly 300,000 people living in communities around Kanlaon on Negros Island, the glow is the latest escalation in a volcanic crisis that began with a violent eruption on December 9, 2024. That event sent an ash column more than three kilometers into the sky, displaced over 80,000 residents, and killed at least one person. The volcano has remained at Alert Level 2, indicating increasing unrest, ever since.
What the instruments are showing
PHIVOLCS calls the glow “banaag,” a Filipino word for faint luminescence, and attributes it to superheated volcanic gases escaping through the summit. But the agency’s concern goes deeper than what the cameras captured. Seismic sensors beneath Kanlaon have recorded a pattern of earthquakes that PHIVOLCS has linked to rock fracturing driven by rising magma and magmatic gas. The agency has also flagged elevated sulfur dioxide (SO₂) emissions as a chemical signature that typically accompanies fresh magma pushing closer to the surface, though it has not released specific flux figures for the days surrounding the crater glow observations.
Taken together, the seismicity, the elevated SO₂, and now the visible crater glow form a pattern that volcanologists recognize as a system under increasing pressure. PHIVOLCS has been explicit about what a shift to Alert Level 3 would mean: the agency lists pyroclastic density currents, or PDCs, as the primary threat. These are fast-moving avalanches of superheated gas and volcanic debris that can barrel down slopes at extreme speed, incinerating everything in their path. Lahars, volcanic mudflows triggered when rain mixes with loose ash and debris, represent a secondary danger that can strike communities far from the summit weeks or even months after an eruption.
In its most recent advisories, PHIVOLCS has stressed close monitoring and lahar preparedness as immediate priorities for local governments. The permanent danger zone around the crater remains strictly enforced, with hikers, farmers, and residents barred from the area due to the risk of sudden explosions and rockfall. Aviation authorities have also been advised to reroute flights away from the summit when ash emissions are detected.
What scientists still don’t know
The crater glow confirms that something hot is close to the surface, but several critical questions remain unanswered. PHIVOLCS has not publicly disclosed whether ground deformation data, such as tilt meter readings or GPS displacement measurements, show the kind of swelling that would indicate magma is actively pushing the mountain outward. Without that information, the speed at which conditions could deteriorate is difficult to pin down.
The timeline for a potential eruption is also framed in deliberately general terms. PHIVOLCS has stated that another eruption “in the next few days” could trigger a Level 3 alert but has stopped short of assigning a probability or a specific window. That caution is standard in volcanology, where false precision can cause more harm than honest uncertainty. But for farmers tending crops on Kanlaon’s slopes and families weighing whether to leave their homes, the ambiguity translates into real strain on livelihoods and nerves.
There is also no public estimate of how many people fall within the expanded danger zones that a Level 3 alert would activate. The December 2024 eruption overwhelmed some local shelters and strained transportation networks. Whether those gaps have been addressed in the months since is unclear. Local government units in Negros Occidental and Negros Oriental maintain their own disaster response plans, but the coordination between municipal, provincial, and national agencies during a rapid escalation has not been tested at Level 3 during this unrest cycle.
Kanlaon’s own history adds another layer of uncertainty. The Smithsonian’s Global Volcanism Program catalogs both phreatic (steam-driven) explosions and magmatic eruptions in the volcano’s record. The current signs could still resolve into either outcome. Magma can stall at depth, degas, and never breach the surface. It can also accelerate without much additional warning.
What residents are being told to do now
For communities on Negros Island, the practical message from PHIVOLCS is straightforward: treat the current unrest as serious and prepare to move quickly if the alert level rises. That means staying out of the permanent danger zone, reviewing evacuation routes, stockpiling supplies, and making plans for livestock and crops that can be sustained over weeks rather than just a few days.
PHIVOLCS has urged residents to rely on official bulletins rather than social media, where unverified claims about eruption timelines have circulated during previous episodes of unrest. The agency’s advisories, posted through the Philippine Information Agency and local government channels, remain the most reliable source of guidance on exclusion zones, alert-level changes, and specific evacuation instructions.
Why the crater glow changes the calculus for Negros Island
The glow photographed on May 9 is a vivid reminder that the system beneath Kanlaon is active, releasing heat, fracturing rock, and venting gas as magma moves at depth. Whether that process builds toward a major eruption or gradually subsides, the current episode has already made one thing clear: the volcano that looms over Negros Island is not settling down.
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*This article was researched with the help of AI, with human editors creating the final content.
