The Philippine Institute of Volcanology and Seismology (Phivolcs) said Kanlaon Volcano recorded its second-highest ever sulfur dioxide (SO2) emissions, following its “explosive eruption” on June 3.

Based on Phivolcs’ volcano bulletin released on Wednesday, June 5, SO2 emissions from Kanlaon Volcano reached 4,133 tons per day when it was last measured on June 4.

This marks the highest flux of SO2 emissions this year and the second-highest ever measured from Kanlaon.

Phivolcs noted that the June 3 eruption was “immediately succeeded by profuse degassing from the summit crater that waned by 8:20 a.m. on June 4.”

“Volcanic SO2 gas emission has been unsteadily increasing since May 2023 and has averaged 1,273 tons per day this year, substantially above the background emission of <300 tons per day,” it pointed out.

Phivolcs also noted that Kanlaon Volcano has experienced increased seismic activity in the past 24 hours, with 53 volcanic earthquakes recorded.

“Kanlaon has been exhibiting periodic swarms of VT (volcanic tremor) earthquakes since Alert Level 1 was raised in March 2020. Since 2023 alone, five advisories on increased seismic activity have been released, the latest of which was last May 26, 2024,” it said.

Alert Level 2 maintained

Phivolcs said Alert Level 2 is still in effect as Kanlaon Volcano is still experiencing “moderate” volcanic unrest.

This indicates the presence of elevated levels of any of the following parameters: volcanic earthquake, temperature, acidity, and volcanic gas concentrations in monitored springs and fumaroles, steam and ash explosions from the summit crater or new vents, and inflation or swelling of the edifice.

Phivolcs reminded the public that entry into the four-kilometer radius permanent danger zone (PDZ) is strictly prohibited.

Some parts of these barangays (villages) are located within the PDZ, which includes Ara-al and Yubo in La Carlota City; Sag-ang, Mansalanao, Cabagnaan, and Biaknabato in La Castellana; Minoyan, Murcia; Masolog, Pula, and Lumapao in Canlaon City; and Codcod in San Carlos City.

Phivolcs urged the local government units, disaster officials, and the public to avoid the PDZ because the likelihood of similar explosive eruptions occurring is high, increasing the threat of volcanic hazards such as pyroclastic density currents and ballistic projectiles within the PDZ.

It noted that Kanlaon occasionally has phreatic and short-lived explosive eruptions that cause minor hazards. 

Of the 43 eruptions recorded since 1866, Phivolcs said only the 1902 eruption was magmatic.

Phreatic eruption involves water coming into contact with hot volcanic materials—hot gases or hot rocks—leading to explosive steam, while the magmatic eruption is driven by the release of magma and volcanic gases.

Kanlaon Volcano’s last phreatic eruption occurred in December 2017.