Sulfur dioxide emissions rise again at Kanlaon volcano in Philippines
Kanlaon volcano in the central Philippines emitted 2 679 tons of sulfur dioxide on June 16, 2025, with five volcanic earthquakes recorded in the same 24-hour period. The volcano remains at Alert Level 3 as signs of elevated unrest persist.
Image credit: PHIVOLCS
Kanlaon volcano, located on Negros Island in the central Philippines, emitted 2 679 tons of sulfur dioxide (SO2) on June 16, consistent with elevated degassing levels observed in recent weeks. Five volcanic earthquakes were recorded during the same period. Alert Level 3 remains in effect due to ongoing unrest.
From May 28 to June 3, daily sulfur dioxide emissions ranged between 300 and 1 844 tons. This increased to a range of 1 355–5 324 tons per day between June 4 and June 10. After briefly subsiding to around 1 326 tons on June 15, SO2 emissions surged again on June 17.
Seismic activity remains moderate, with 3 to 26 small earthquakes detected daily over the past week. The latest report from the Philippine Institute of Volcanology and Seismology (PHIVOLCS), published on June 17, reported five volcanic earthquakes during the preceding 24-hour observation period.
Continuous degassing from the summit crater has been producing steam-laden plumes rising up to 300 m (980 feet), dispersing toward the north-northwest, north, and northeast. Ground deformation data indicate persistent inflation of the volcanic edifice, indicating pressure buildup at shallow depth.
PHIVOLCS warns that hazardous volcanic activity, including sudden explosions, lava effusion, ashfall, pyroclastic density currents, and lahars during periods of intense rainfall, remains possible.
Communities within the 6 km (3.75 miles) Permanent Danger Zone (PDZ) have been urged to evacuate, and authorities have banned entry into this zone. Civil aviation is also advised to avoid flying near the summit due to the risk of explosive eruption.
Kanlaon volcano has shown intermittent eruptive behavior since June 2024, with explosive episodes occurring in May 2025, April 2025, and December 2024. Sulfur dioxide emissions have spiked above 10 000 tons per day during peak activity in the past.
References:
1 Kanlaon Volcano Summary of 24Hr Observation 17 June 2025 – PHIVOLCS – June 17, 2025
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