The Philippine Institute of Volcanology and Seismology (Phivolcs) has issued a notice of increased seismic and ground deformation activity at Kanlaon Volcano, which may lead to the raising of Alert Level 2.
Between 10:25 PM of May 3 and 4:00 PM of May 4, the volcano’s monitoring network recorded 20 volcanic earthquakes ranging in energy from ML1.2 to ML2.4, occurring at shallow depths down to 6 kilometers beneath the summit crater.
Additionally, Phivolcs noted that the southeast middle slopes have been undergoing an episode of pronounced inflation since the second week of April 2023.
In its 8:30PM advisory, Phivolcs added that the volcanic sulfur dioxide (SO2) gas emission from the summit crater averaged 632 tonnes/day on May 1, higher than the average emission of 246 tonnes/day since March 2023.
It has also detected SO2 concentrations for the first time in continuously monitored thermal springs on the northwestern flanks of the volcanic complex.
According to Phivolcs these parameters likely indicate shallow hydrothermal activity driven by degassing of deeper magma, with increased possibilities of phreatic or steam-driven explosions occurring at the summit crater.
At present, the volcano remains under Alert Level 1, however should an uptrend in monitoring parameters persist, Phivolcs may raise the alert level to 2 to warn of increasing unrest.
The public and local government units are strongly advised to be vigilant and refrain from entering the four (4) kilometer Permanent Danger Zone (PDZ) due to increased chances of sudden and hazardous phreatic eruptions occurring without warning.
Civil aviation authorities are also directed to advise pilots to avoid flying close to the volcano’s summit as ejecta from any sudden phreatic eruption can be hazardous to aircraft.