The Philippine Institute of Volcanology and Seismology (Phivolcs) detected 288 volcano-tectonic earthquakes at Kanlaon Volcano due to rising seismic activity, which indicates “increasing unrest.”

In an advisory issued at 11 a.m. on Monday, Sept. 9, Phivolcs said the quakes observed at Kanlaon Volcano since 8:30 p.m. on Sept. 9 occurred at depths of zero to 9 kilometers beneath the northeastern flanks of the volcano.

The strongest events were felt at Intensity II in some barangays of Canlaon City, Negros Oriental, and rumbling sounds were reported by residents of Bago City.

Phivolcs also received reports of strong sulfur fumes in a few barangays in Bago, La Carlota, and Canlaon cities.

It explained that volcano-tectonic earthquakes result from rock-fracturing processes, and the increase in seismic activity strongly suggests progressive rock-fracturing beneath the volcano as rising magma moves toward the surface.

Phivolcs reminded the public that Alert Level 2 (increasing unrest) is currently in effect for Kanlaon Volcano.

However, the ongoing seismic activity raises the possibility of further unrest and a potential upgrade in the alert level, it added.

Residents are advised to remain vigilant and avoid entering the four-kilometer-radius permanent danger zone to minimize risks from volcanic hazards such as pyroclastic density currents, ballistic projectiles, and rockfalls.

In the event of ash fall affecting communities downwind of Kanlaon Volcano's crater, Phivolcs said individuals should cover their noses and mouths with a damp, clean cloth or dust mask. 

Civil aviation authorities are asked to advise pilots to steer clear of the volcano summit to avoid hazards from ash and volcanic fragments.

Likewise, communities living near river systems on the southern and western slopes, especially those previously affected by lahars and muddy streamflows, are advised to take precautionary measures if heavy rainfall is anticipated or begins.