The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported 41 volcanic earthquakes at Kanlaon Volcano since June 30.
The Kanlaon Volcano Network (KVN) said in an advisory that the tremors included seven very shallow tornillo signals associated with volcanic gas movement and fractures in the upper volcanic slopes.
Furthermore, it was noted that ground deformation data from continuous GPS measurements showed slight short-term inflation of the lower and mid slopes beginning in January 2022.
"These are consistent with continuous electronic tilt recording of southeastern flank inflation since mid-March 2022," the PHIVOLCS stated.
"The increased seismic activity and short-term ground deformation are most likely caused by shallow hydrothermal processes beneath the edifice, which could generate phreatic or steam-driven eruptions from the summit crater," the agency added.
The Kanlaon Volcano was placed on Alert Level 1 by PHIVOLCS. This meant that the volcano was in a stable state.
Nonetheless, the institute warned local governments and the general public that entering the four-kilometer-radius Permanent Danger Zone (PDZ) must be strictly prohibited due to the possibility of additional sudden and dangerous steam-driven or phreatic eruptions.
PHIVOLCS also urged civil aviation authorities to warn pilots not to fly too close to the volcano's summit because ejecta from a sudden phreatic eruption can be dangerous to aircraft.