The Philippine Institute of Volcanology and Seismology (Phivolcs) has monitored slightly increased seismic activity and volcanic gas flux at Mt. Kanlaon in the past few days.
In an advisory issued on Saturday evening, Feb. 13, Phivolcs said its monitoring network has detected 28 volcanic earthquakes between Feb. 11 and Feb. 13.
These earthquakes ranged in energy from magnitude 0.7 to magnitude 2.2 and occurred at shallow depths at 10 kilometers across the northern to eastern portions of the edifice, it said.
Moreover, sulfur dioxide gas emission from the summit crater reached an average of 1,130 tonnes per day, the highest value recorded this year, following a trend since June 2020 of emissions higher than background levels of 300 tonnes per day, Phivolcs pointed out.
It also noted that ground deformation data from continuous GPS (global positioning system) and electronic tilt measurements have been recording a slight inflation of the lower and middle slopes since June 2020, indicating slow pressurization within the volcano.
"These parameters could indicate hydrothermal, tectonic or even deep-seated magmatic processes occurring beneath the edifice," Phivolcs said.
"The observational parameters signify that Kanlaon is in a restive state, with increased possibilites of phreatic or steam-driven explosions occurring at the summit crater," it added.
Phivolcs urged the public to be vigilant and refrain from entering the four-kilometer permanent danger zone due to possible sudden and hazardous phreatic eruptions.
Civil aviation authorities were asked to advise pilots to avoid flying close to the volcano's summit as ejecta from any sudden phreatic eruption can be hazardous to aircraft.