Mount Kanlaon, one of the Philippines’ most active volcanoes, is showing alarming signs of escalating unrest, prompting the Philippine Institute of Volcanology and Seismology (PHIVOLCS) to issue a stern warning of a possible upgrade to Alert Level 3. This heightened vigilance follows the clear visibility of a persistent crater glow, known locally as “banaag,” over the weekend, coupled with an ash emission detected in the early hours of Monday. These critical developments signal that magma may be nearing the surface, significantly increasing the likelihood of a more substantial eruption.
An elevation to Alert Level 3 would signify a "high level of unrest," indicating that a magmatic eruption has either commenced or is imminent. Such an event carries the grave potential for life-threatening hazards, including pyroclastic density currents and widespread ashfall, impacting thousands of residents living within the volcano's immediate vicinity on Negros Island.
PHIVOLCS issued an advisory on Monday, May 11, detailing the concerning observations from the summit of Kanlaon. While the volcano currently remains under Alert Level 2, indicating a moderate level of volcanic unrest, the agency explicitly stated that a sustained and intensifying crater glow could swiftly trigger an elevation to Alert Level 3.
The most striking new development is the direct visual confirmation of incandescence within the summit crater. Personnel at the Kanlaon Volcano Observatory (KVO) in Negros Occidental first reported observing this phenomenon with the naked eye around 7 p.m. on Sunday, May 10. This visible glow marks a significant escalation from previous monitoring, which had relied on infrared and high-resolution cameras to detect superheated volcanic gas emissions since November 2024. These thermal plumes have shown increased frequency since April 13 of this year, but the appearance of "banaag" to the naked eye is considered a significant precursor to magmatic eruptions in other Philippine volcanoes, such as Mayon.
Further underscoring the escalating situation, a volcanic ash advisory was issued on May 10 at 7:51 p.m. UTC, which corresponds to 3:51 a.m. local time on May 11. The advisory reported an eruption that generated an ash cloud reaching an approximate altitude of 10,000 feet. This event confirms that Kanlaon is no longer merely exhibiting precursory signs of unrest but is already engaging in active eruptive behavior, albeit currently on a minor scale. The combination of sustained crater glow and recent ashfall paints a picture of a volcano growing increasingly volatile.
Volcanologists are meticulously tracking several other parameters that collectively point to a deeply restive state beneath the volcano. Seismic activity around Kanlaon has remained consistent, with an average of six volcano-tectonic earthquakes recorded daily, indicating ongoing stress within the volcano's structure.
More notably, sulfur dioxide (SO2) gas emissions, a key indicator of magma degassing, have shown a concerning uptick. While campaign mDOAS measurements previously averaged 1,646 tonnes per day, they have slightly increased to 2,382 tonnes per day in the past week. This rise in SO2 levels suggests that magma is moving closer to the surface, releasing more gases as pressure decreases.
Ground deformation surveys also provide a worrying trend, indicating a sustained and slow-rate inflation of the volcano's edifice since 2022. This continuous inflation suggests that magma is persistently pushing upwards from beneath, causing the ground surface to swell and stressing the volcano's structural integrity.
PHIVOLCS acknowledged that while the naked-eye observation of the crater glow is a new and critical development, the overall monitoring parameters have largely persisted at similar elevated levels since Kanlaon's last moderately explosive eruption on March 15, 2026. That eruption was one of three such events recorded in the first quarter of this year, demonstrating Kanlaon's inherent dynamism and its propensity for explosive activity. The current situation, however, with the visible glow and recent ash emission, suggests a qualitative shift in the nature of its unrest, signaling a potentially more imminent and hazardous phase.
An upgrade to Alert Level 3 would necessitate stringent measures due to the severe and immediate hazards associated with magmatic eruptions. These include pyroclastic density currents (PDCs), which are fast-moving, destructive mixtures of hot volcanic fragments, gases, and ash that sweep down slopes at high speeds, posing an undeniable threat to life. Other dangers include lava flows, ballistic projectiles (volcanic bombs that can be hurled great distances), significant ashfall that can severely impact communities, agriculture, and air travel, and destructive rockfalls. Such phenomena pose direct threats to human life and critical infrastructure within the volcano's immediate vicinity.
In anticipation of such possibilities, PHIVOLCS has reiterated its strong recommendation for communities within the 4-kilometer Permanent Danger Zone (PDZ) around Kanlaon's summit to strictly remain evacuated. Residents living in areas identified as Pyroclastic Density Current Hazard Zones are advised to maintain heightened vigilance and be prepared for immediate evacuation should the volcanic unrest intensify further. Local government units and disaster risk reduction officials are urged to prepare robust response measures and stay alert for "potential syn-eruption lahars and sediment-laden streamflow in channels" during periods of heavy rainfall, which could mobilize fresh volcanic deposits into destructive mudflows.
The Philippines, situated within the seismically and volcanically active "Pacific Ring of Fire," is no stranger to the unpredictable forces of nature. Mount Kanlaon, standing prominently on Negros Island, has a long history of activity, making it one of the archipelago's most closely watched volcanoes. The recent moderately explosive eruption on March 15, 2026, and the two others preceding it earlier that year, serve as stark reminders of the volcano's persistent potential for sudden and forceful displays.
PHIVOLCS plays a crucial role in monitoring these geological hazards, providing timely warnings, and guiding public safety efforts across the nation. The ongoing situation at Kanlaon Volcano underscores the continuous need for preparedness and adherence to expert advisories among the communities living in the shadow of this formidable natural landmark. Understanding the nuances between Alert Level 2, which signifies moderate unrest, and Alert Level 3, which indicates a high level of unrest and an imminent or ongoing magmatic eruption, is vital for public safety.
The coming days will be critical as volcanologists continue to watch for any further intensification of activity at Kanlaon, meticulously analyzing every data point from seismic tremors to gas emissions. Their observations will determine whether the persistent crater glow is merely a flicker of deep-seated magma or the herald of a more forceful display of nature's power. The fate of thousands of residents hinges on these observations and the proactive decisions made in response.