PHIVOLCS reported that intense rain on 6 June mobilized ash deposited during the 3 June eruption at Kanlaon causing lahars to descend the S flank and impact local communities. The lahars began at around 1300 and lasted 25 minutes based on seismic data. They deposited cohesive gray mud, plant debris, and gravel in at least four stream channels including Tamburong Creek, which courses through Biak-na-bato and Calapnagan, La Castellana; Intiguiwan River in Guinpanaan and upstream Baji-Baji Falls in Cabacungan, La Castellana; Padudusan Falls, Masulog, Canlaon City; and the Binalbagan River, which drains the S flank of the volcano. Lahars overflowed parts of Tamburong Creek and deposited material a few centimeters thick along a section of the main road in Biak-na-Bato, making it impassable to motorists. Thunderstorms continued and channel-confined lahars on the S and W flank were detected the next day. The lahars began at around 1450 on 7 June and lasted 80 minutes based on seismic data. They were described as cohesive and cement-like and carried tree debris along the Baji-Baji Falls and Ibid Creek, in Cabacungan, La Castellana. Lahars also descended the Santo Guintubdan, Ara-al, La Carlota City and muddy waters were observed in the Buslugan, Busay Oro, Busay Abaga, Busay Mayor, Busay Kapid, Kabkaban, Ezzy, Busay Ambon, and Labi Labi falls. Voluminous gas-and-steam emissions rose 1.5-2 km above the summit and drifted NE and SW during 6-8 June.

A special notice was issued on 8 June due to elevated sulfur dioxide levels. During a field survey sulfur dioxide flux averaged of 4,397 tonnes per day (t/d) which was the highest level recorded so far this year and the second highest land-based measurement for Kanlaon. Sulfur dioxide emissions were elevated in 2024, averaging 1,458 t/d, though after the 3 June eruption the daily average increased to 3,347 t/d. Emisisons had decreased on 9 June, averaging 3,304 t/d. The rate of volcanic earthquakes persisted at above-background levels with an average of 33 events per day. Moderate steam-and-gas emissions rose 300-500 m above the summit and drifted NE and SW during 9-11 June. At least 1,237 families or 4,190 residents of five barangays remained in evacuation shelters according to a 12 June news article; many had health problems from exposure to sulfur dioxide gas and ash. 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 island of Negros, Philippines. 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.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS), The Philippine Star