By Ellalyn De Vera-Ruiz
Kanlaon Volcano in Negros Island remains under Alert Level 1 amid an ongoing volcanic activity-triggered earthquakes occurring since last week.
During the Philippine Institute of Volcanology and Seismology's (Phivolcs) 24-hour monitoring from 8 a.m. on Saturday, June 27 to 8 a.m. on Sunday, June 28, Kanlaon Volcano's seismic monitoring network recorded 30 volcano-tectonic earthquakes on the western flanks and one volcanic earthquake in the summit area.
However, these earthquakes were too small to be felt.
Phivolcs said a moderate emission of white steam-laden plumes that rose 300 meters before drifting northwest was also observed from the volcano summit.
It also noted that the sulfur dioxide (SO2) emission was measured at an average of 116 tonnes per day. The presence of significant sulfur dioxide from a volcano could indicate that magma is still getting closer to the surface.
According to Phivolcs, ground deformation data from continuous GPS measurements indicate a slight deflation of the lower and mid-slopes since January this year.
"Short-term electronic tilt monitoring on the southeastern flanks recorded continuing deflation on the lower slopes but inflation on the mid slopes since April 2020," it said.
"These parameters indicate that hydrothermal or magmatic activity is occurring beneath the edifice," it pointed out.
Kanlaon Volcano has been under Alert Level 1, the lowest on a five-tier scale, since March 11, 2020. It means the active volcano is at an abnormal condition and has entered a period of unrest.
Phivolcs warned the public that entry into the four-kilometer permanent danger zone is strictly prohibited due to possible sudden and hazardous steam-driven or phreatic eruptions.
Furthermore, civil aviation authorities were asked to advise pilots to avoid flying close to the volcano's summit as airborne ash and ballistic fragments from sudden phreatic eruption may pose hazards to aircrafts.