Kanlaon Volcano on Negros Island is in a restive state, with increased possibilities of phreatic or steam-driven explosions occurring at the summit crater, the Philippine Institute of Volcanology and Seismology (Phivolcs) warned in an advisory issued Saturday night, February 13.
Phivolcs said the advisory was issued after slightly increased seismic activity and volcanic gas flux at Kanlaon Volcano was observed.
Kanlaon Volcano’s monitoring network recorded 28 volcanic earthquakes between February 11 and 13.
However, Phivolcs at 8 a.m. today, February 14, reported a drop in volcanic earthquakes to seven during the 24-hour observation period.
There was heightened activity at the volcano but so far it is still under alert level 1, Provincial Disaster Management Program Division head Zeaphard Caelian said today.
Rain that falls into the smoldering volcano could trigger phreatic explosions, Caelian said.
Caelian said if Phivolcs raises the alert level at Kanlaon the provincial government has corresponding responses in place.
Phivolcs reported that Kanlaon today had moderate emission of white steam-laden plumes that rose 500 meters before drifting southeast and northwest was observed.
It reiterated that ground deformation data from continuous GPS and electronic tilt measurements have been recording a slight inflation of the lower and middle slopes since June 2020.
These parameters may indicate hydrothermal or magmatic processes occurring deep beneath the edifice, it added.
On Saturday night, February 13, Phivolcs said the 28 volcanic earthquakes it recorded ranged in energy from ML0.7 to ML2.2 and occurred at shallow depths to depths of 10 kilometers across the northern to eastern portions of the edifice.
Sulfur dioxide (SO2) gas emission from the summit crater Saturday reached an average of 1,130 tons in a day, the highest value recorded this year, following a trend since June 2020 of emissions higher than background levels of 300 tons a day, Phivolcs reported.
Phivolcs reiterated that the public is strongly advised to be vigilant and to refrain from entering the four kilometer Permanent Danger Zone because sudden and hazardous phreatic eruptions may occur without warning.
Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ejecta from any sudden phreatic eruption can be hazardous to aircraft, it added.*