Phivolcs observes 'elevated' sulfur dioxide emissions at Kanlaon Volcano

An elevated volcanic sulfur dioxide (SO2) gas flux was observed by the Philippine Institute of Volcanology and Seismology (Phivolcs) as it continues to monitor new developments at Kanlaon Volcano closely.

Kanlaon Volcano spewing thick plume as seen from Barangay Pula, Canlaon City in Negros Occidental on June 3, 2024. (Photo courtesy of Ethan Asentista-Khoo)

“This is the highest emission this year measured by campaign survey and the second highest land-based measurement for Kanlaon,” Phivolcs said in the volcano bulletin released Saturday night, June 8.

The volcanic SO2 gas emission from the summit crater of Kanlaon, Phivolcs said, averaged 4,397 tons per day.

Phivolcs also noted that Kanlaon Volcano has been “degassing increased concentrations of volcanic SO2” this year at an average rate of 1,458 tons per day.

However, Phivolcs observed that the emission since Kanlaon’s eruption on June 3 has been particularly “elevated” at a current average of 3,347 tons per day.

Phivolcs also pointed out that the background volcanic earthquake activity has “persisted” at an average of 33 events per day since the eruption.

“Ground deformation data from continuous GPS and electronic tilt measurements have been recording medium-term inflation of the Kanlaon edifice since March 2022 and shorter-term inflation of the eastern flank since 2023, indicating slow pressurization within the volcano,” Phivolcs said.

“The overall monitoring parameters indicate that degassing of magma may be driving current unrest, causing increased volcanic gas emission, swelling of the edifice, and occasional volcanic earthquake activity,” it added.

Alert Level 2 prevails

Meanwhile, Phivolcs reminded the public that Alert Level 2 prevails over Kanlaon.

“This means that there is current unrest driven by shallow magmatic processes that could eventually lead to explosive eruptions at the summit crater,” Phivolcs said.

Phivolcs also advised the public to be “vigilant” and avoid the four-kilometer-radius Permanent Danger Zone (PDZ) to minimize risks from volcanic hazards such as pyroclastic density currents, ballistic projectiles, rockfall, and others.

In case of ashfall events that may affect communities downwind of Kanlaon’s crater, Phivolcs reminded affected individuals to cover their noses and mouths with a damp, clean cloth or dust mask.

“Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash and ballistic fragments from sudden eruptions can be hazardous to aircraft,” Phivolcs said.

Moreover, Phivolcs warned communities living beside river systems on the southern and western slopes, especially those that have already experienced lahars and muddy streamflows, to “take precautionary measures” when heavy rainfall over the volcano has been forecast or has begun.