MANILA, Philippines – State volcanologists alerted the public of an increase in volcano-tectonic (VT) earthquakes at Kanlaon Volcano in Negros Island on Thursday, October 31.
The Philippine Institute of Volcanology and Seismology (Phivolcs) said in an advisory at 10:30 am on Thursday that at least 64 VT earthquakes have been recorded since 12 am, or in just 10.5 hours.
The VT earthquakes were 2 to 8 kilometers deep, located “beneath the southwestern flanks of the volcanic edifice,” and had magnitudes ranging between 0.9 and 2.9.
“VT earthquakes are generated by rock fracturing processes and the increase in VT activity strongly indicates progressive rock fracturing beneath the volcano as rising magma drives a path towards the surface,” Phivolcs said.
Sulfur dioxide (SO2) emission from Kanlaon has also been considerably high since the volcano erupted last June 3, averaging 4,234 tons per day.
On Wednesday, October 30, it averaged 7,087 tons per day, and just last Monday, October 28, it soared to 10,074 tons per day, which is Kanlaon’s fifth highest emission “since instrumental gas monitoring began.”
Prior to the June eruption, the average was already relatively high, at 1,273 tons per day. When the volcano is not in a state of unrest, the typical emission is less than 300 tons per day.
Kanlaon remains under Alert Level 2, but Phivolcs said the current spike in VT earthquakes “may lead to eruptive unrest and an increase in the alert level.” Alert levels range from 0 (normal) to 5 (hazardous eruption in progress).
“The public is strongly advised to be ready and vigilant,” the agency said.
Phivolcs also reminded the public not to enter the 4-kilometer-radius permanent danger zone around the volcano “to minimize risks from volcanic hazards such as pyroclastic density currents, ballistic projectiles, rockfall, and others.”
Ashfall and lahar flows remain possible as well. – Rappler.com