Kanlaon Volcano has entered a period of unrest and is now under Alert Level 1 (abnormal condition), the Philippine Institute of Volcanology and Seismology (Phivolcs) announced.

There were 80 volcanic earthquakes recorded since March 9, and these are dominated by 77 low-frequency events associated with magmatic fluids beneath the edifice, Phivolcs said.

Volcanic earthquakes are caused by movements or eruptions of magma from the volcano, compared to tectonic quakes which are caused by fault movements.

“The increased seismic activity could be succeeded by steam-driven or phreatic eruptions at the summit crater, despite the absence of visible degassing or steaming from the active vent this year,” it said in its bulletin.

Volcanic plume is a column of hot volcanic ash and gas emitted into the atmosphere during an explosive volcanic eruption. A weaker eruption is based on the height of the plume coming out of the crater.

Meanwhile, Phivolcs reminded the public and local government units that entry into the four-kilometer radius Permanent Danger Zone (PDZ) must be strictly prohibited due to the possibilities of sudden and hazardous phreatic eruptions.

Aviation authorities should advise pilots to avoid flying close to the volcano’s summit, as materials thrown out from any sudden phreatic eruption can be hazardous to aircraft, Phivolcs said. (PNA)