PHIVOLCS issued special notices for Kanlaon noting continuing high levels sulfur dioxide gas emissions. Summit emissions measured with a Flyspec instrument averaged 6,720 tonnes/day (t/d), 6,367 t/d, and 7,172 t/d on 21, 24, and 25 August, respectively. Sulfur odors were reported in several barangays (neighborhoods) in La Carlota City (14 km W) and La Castellana (16 km SW), Negros Occidental, on 21 August and in Murcia (17 km NNW), Negros Occidental, on 24 August. Voluminous steam-rich plumes were observed on 24 August rising as high as 700 m above the crater rim and drifting N. The 25 August measurement was the second highest emission average ever recorded at the volcano. Sulfur dioxide emissions decreased to 3,447 t/d on 26 August.

Higher sulfur dioxide gas fluxes had been recorded in 2024 with an average of 1,273 t/d prior to the 3 June eruption; afterward the eruption emissions were elevated, averaging 3,351 t/d. An average of nine volcanic earthquakes per day also persisted after the 3 June eruption. Ground deformation data from continuous GPS and electronic tilt data indicated slow inflation of the volcano since March 2022; the rate of inflation at the E flank increased in 2023 and at the SE flank beginning in July 2024. The Alert Level remained at 2 (on a scale of 0-5) and PHIVOLCS reminded the public to remain outside of the 4-km-radius Permanent Danger Zone.

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)