The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing unrest and an ash emission at Kanlaon during 9-16 September. Daily gas-and-steam emissions of variable densities rose 300-900 m above the crater rim and drifted E, NW, W, and SW. Daily sulfur dioxide emissions ranged from 1,031 to 2,338 tonnes per day (t/d); the average was 2,594 t/d in 2025. A 20-minute-long ash emission began at 0510 on 10 September and produced ash plumes that rose 600 m and drifted WSW. A total of 41 volcano-tectonic (VT) earthquakes were detected from 2200 on 13 September to 1000 on 14 September that were located at depths of 0-7 km beneath the NW flank. The strongest events were classified at Intensity III and felt in La Carlota City (14 km W), Bacolod City (35 km NW), and Canlaon City (10 km ESE), Negros Oriental, as well as in Bago City (30 km NW), Murcia (17 km NNW), and La Castellana (16 km SW), Negros Occidental. During 0000-0800 on 15 September the seismic network recorded 72 VT earthquakes located at depths of 0-12 km. The events were 0.8-3.6 local magnitudes. The strongest events were classified at Intensity I and felt in La Carlota City and Canlaon City. The Alert Level remained at 2 (on a scale of 0-5); the public was warned to stay out of the 4-km-radius Permanent Danger Zone (PDZ) and pilots were advised to avoid flying close to the summit.

Geological Summary. Kanlaon volcano (also spelled Canlaon) forms the highest point on the Philippine island of Negros. The massive andesitic stratovolcano is covered with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km SW from Kanlaon. The summit contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller but higher active vent, Lugud crater, to the south. Eruptions recorded since 1866 have typically consisted of phreatic explosions of small-to-moderate size that produce minor local ashfall.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)