On the night of May 9, 2026, cameras at the Kanlaon Volcano Observatory in Canlaon City captured something that had not appeared during the volcano’s current stretch of unrest: a distinct orange-red glow above the summit crater, visible against the dark sky of Negros Island. A second image, taken the following evening, showed the glow again, this time paired with thick plumes of superheated gas rising from the vent. For the Philippine Institute of Volcanology and Seismology (PHIVOLCS), the photographs confirmed what seismic instruments had been suggesting for weeks: fresh magma is pushing close enough to the surface to radiate heat and light into the open air.
The agency has warned that a magmatic eruption could follow in the near term, and PHIVOLCS VMEPD chief Ma. Antonia V. Bornas told a Regional Disaster Risk Reduction and Management pre-disaster risk assessment meeting that another eruption could trigger a raise to Alert Level 3. That would mark a significant escalation and almost certainly widen the mandatory evacuation perimeters around a volcano that sits within reach of tens of thousands of residents in Negros Occidental and Negros Oriental.
Why the crater glow matters
Kanlaon has been restless for months, but much of its recent activity has been phreatic: steam-driven explosions caused by groundwater flashing to vapor on contact with hot rock underground. Phreatic blasts can hurl rocks and ash with little warning, but they tend to be short-lived and localized. A magmatic eruption is a different category of event. When molten rock itself reaches the surface, it can generate sustained ash columns, pyroclastic flows, and lava output that threaten a far wider area over a longer period.
PHIVOLCS scientists have directly linked the ongoing seismic swarms beneath Kanlaon to rising magma and magmatic gas. The crater glow is the visible confirmation of that assessment. Superheated material is now shallow enough to illuminate gas and vapor from below, a signal that the system has moved beyond background unrest into a phase that has, in Kanlaon’s history, preceded some of its more energetic eruptions.
The Smithsonian Institution’s Global Volcanism Program, which maintains a standardized chronology of Kanlaon’s eruptive history stretching back centuries, classifies it as one of the most frequently active volcanoes in the central Philippines. That record shows crater glow episodes have appeared before larger eruptions in the past, though not every glow event has escalated. The historical pattern supports heightened vigilance without guaranteeing a major blast.
The sulfur dioxide question
One of the more closely watched indicators is sulfur dioxide output. According to the Philippine Information Agency, PHIVOLCS has been tracking SO2 degassing averages from two different baselines: one beginning June 3, 2024, and another beginning January 1, 2026. The agency also flagged a notable drop in SO2 emissions immediately before a March 2026 eruption at Kanlaon.
That detail matters because a pre-eruption decline in SO2 can indicate that rising magma has sealed the volcanic conduit, trapping gas beneath a plug of cooling rock. When the plug eventually fails, the stored pressure can produce a more explosive event than the preceding degassing trend would suggest. In plain terms: a volcano that goes quiet on gas output is not necessarily calming down. It may be building toward a bigger release.
The question now is whether the current SO2 pattern mirrors what was observed before the March eruption closely enough to serve as a short-term warning sign. PHIVOLCS has not released the underlying daily measurements publicly, so independent volcanologists cannot yet verify the comparison. The similarity is suggestive, not conclusive.
What happened in March, and what could happen next
The March 2026 eruption at Kanlaon demonstrated that the volcano is capable of producing significant events during its current unrest cycle. PHIVOLCS documented that eruption and its precursors, including the SO2 drop, as part of its ongoing monitoring. The agency has not published a precise probability estimate or firm date window for the next potential eruption, but Bornas’s public remarks about Alert Level 3 signal that internal assessments view escalation as a realistic possibility, not a remote one.
Alert Level 3 on the PHIVOLCS scale indicates that magma is near or at the surface and that hazardous eruption is possible within weeks or sooner. A raise to that level would likely trigger expanded exclusion zones and mandatory evacuations for communities closest to the summit. The current alert level has not been publicly specified in available reporting, an information gap that leaves residents uncertain about exactly where the official assessment stands right now.
Equally unclear is the readiness of local evacuation infrastructure. No detailed public statements from PHIVOLCS or local government units have addressed the current capacity of evacuation shelters, the number of residents within potential danger zones, or contingency plans for moving people, livestock, and harvested crops. For farming communities on Kanlaon’s slopes, where livelihoods depend on timing harvests and protecting irrigation systems from ash contamination, that information gap is not abstract. It shapes daily decisions about whether to stay, prepare, or leave.
What Kanlaon’s communities are facing
Eruption forecasting has improved dramatically in recent decades, but it still cannot deliver the kind of certainty that families living on a volcano’s flanks need most. What PHIVOLCS can offer, through crater glow imaging, seismic monitoring, and gas measurements, is an early warning that the system is changing in ways that have preceded larger eruptions before. The agency’s bulletins and local government advisories remain the most reliable guides for residents weighing their options.
The practical picture is this: visible crater glow, seismicity attributed to rising magma, a possible repeat of the gas pattern that preceded the March eruption, and a named PHIVOLCS official publicly discussing Alert Level 3. Taken together, these indicators describe a volcano in a state of elevated unrest with a real chance of escalation. Taken individually, none of them guarantees a major eruption.
That tension between clear warning signs and irreducible uncertainty is now shaping life below Kanlaon’s summit. On clear nights, the glow is visible from towns that have coexisted with this volcano for generations. The difference this week is that the light is no longer just geological background. It is a signal, watched more closely than ever by the scientists and the communities who both know that Kanlaon can still move faster than any forecast.
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*This article was researched with the help of AI, with human editors creating the final content.
