The Philippine Institute of Volcanology and Seismology (PHIVOLCS) on Friday, July 21, issued a notice of increased seismic activity at Kanlaon Volcano and warned of possible further unrest.
A total 35 volcano-tectonic or VT earthquakes were recorded by the Kanlaon Volcano Network between 10 p.m. Thursday, July 20, and 9:06 a.m. Friday, July 21, PHIVOLCS said.
These earthquakes ranged in energy from ML0.9 to ML2.3 and occurred at depths of 12 to 15 kilometers beneath the summit crater, it said.
While monitoring parameters in the past months have been consistent with shallow hydrothermal activity driven by degassing of deeper magma, ongoing VT earthquake activity indicates that fracturing at deeper levels is occurring and may possibly lead to further unrest, PHIVOLCS said.
Should the uptrend in monitoring parameters persist, the volcano status may be raised to Alert Level 2 to warn of increasing unrest, PHIVOLCS said.
Ground deformation data from continuous GPS and electronic tilt measurements have been recording short-term inflation of the middle slopes since March 2023, PHIVOLCS said.
Volcanic sulfur dioxide (SO2) gas emission from the summit crater averaged 786 tons a day on Tuesday, July 18, slightly higher than the average emission of 566 tons a day since March, it said.
The public is reminded that Alert Level 1 prevails over Kanlaon, PHIVOLCS said.
The public and local government units are strongly advised to be vigilant and refrain from entering the four kilometer Permanent Danger Zone due to increased chances of sudden and hazardous phreatic eruptions occurring without warning, it said.
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.*