KANLAON VOLCANO ERUPTION UPDATE

10 December 2024

03:30 AM

Summary of Observations:

An explosive eruption occurred at the summit vent of Kanlaon Volcano at 3:03 PM yesterday, 9 December 2024, that lasted three (3) minutes and fifty-five (55) seconds based on its seismic record. The event was detected by all thirteen stations of the Kanlaon Volcano Network (KVN) as well as by several stations of the Philippine Seismic Network (PSN) in Central Visayas. The eruption produced a voluminous plume that rapidly rose to 4,000 meters above the vent and was bent and drifted by strong winds to the west-southwest. Ashfall was reported over a wide area west of the volcano, with reports from the following localities:

The smell of sulfur was also reported in the above-specified barangays of Negros Occidental and as far as the town proper of Bago City.

Pyroclastic density currents or PDCs, hazardous mixtures of hot volcanic gas, ash and fragmented rock, were generated at the base of the eruption column and descended the south-southeastern sides of the edifice based on camera monitors. The longest descent of the PDCs from the summit crater was estimated to be approximately 2 to 3.4 kilometers in Masulog, La Castellana, still within the four-kilometer radius Permanent Danger Zone (PDZ). Local government units reported the following areas that were impacted by PDCs.

In addition, the explosive eruption produced a strong pressure or shock wave that was experienced as a loud booming sound and rattled objects within at least a thirty-kilometer radius of the volcano summit based on social media data. Infrasound stations of the Kanlaon Volcano Network (KVN) located approximately five kilometers from the crater recorded the pressure wave at 150 Pa or 138 dB SPL, levels that could be harmful to human hearing. Weaker infrasound signals were also recorded by stations of Mayon and Bulusan Volcano Networks.

Prior to the eruption, emissions from the summit were noticeably weaker than past days, resulting in a lower SO₂ flux average 1,669 tonnes/day measured earlier in the day. Only six weak-volcano-tectonic earthquakes were detected for the day and no precursory seismic activity preceded the eruption. Ground deformation monitors have been detecting short-term inflation of upper southeast flank since late November 2024, indicating pressurization in the shallow parts of the edifice. However, this inflation phase was much weaker than deformation recorded in the third week of June to July 2024, at which time no eruptive activity transpired. Kanlaon has also been emitting ash aseismically (no seismic signal) since 19 October 2024. Microscopic examination of 23 samples of the most significant of some 90 detected ash emissions revealed that the ashes have been wholly composed of pulverized old rock within the volcano and bore no fragments from new magma. Ash from the 9 December 2024 eruption has been collected for similar analysis in order to help evaluate the triggers of this event.

Recommended Actions:

Alert Level 3 (magmatic unrest) has now been raised over Kanlaon Volcano. This means that  there are increased chances for sudden and even stronger explosive eruptions to occur and endanger communities at risk with life-threatening volcanic hazards. It is therefore recommended that communities within a six-kilometer radius of the summit crater be evacuated due to the danger of pyroclastic density currents or PDCs, ballistic projectiles and ashfall, lava flows, rockfalls and other related hazards. Local government units and DRRM councils must also vigilantly monitor weather conditions in case heavy rainfall occurs and generates lahars and sediment-laden streamflows in channels draining the southern flanks of the volcano. Specifically, barangays of La Castellana and Canlaon City listed above that have been impacted by PDCs, as well as barangays downstream of these especially those that have experienced lahars and muddy streamflows in June 2024, could be affected by lahars in case of heavy rains. Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden eruption can be hazardous to aircraft. Lastly, local government units and DRRM councils are advised to prepare communities within the DOST-PHIVOLCS Pyroclastic Density Currents Hazard Map for potential evacuation in case unrest further escalates and hazardous worst-case explosive eruption becomes imminent.

DOST-PHIVOLCS maintains close monitoring of Kanlaon Volcano and any new development will be communicated to all concerned stakeholders.

DOST-PHIVOLCS