MANILA, Philippines – Volcanic earthquakes have increased at Kanlaon Volcano in Negros Island, said the Philippine Institute of Volcanology and Seismology (Phivolcs) on Friday, July 21.

Phivolcs data showed there were 35 volcano-tectonic earthquakes between 10 pm, Thursday, July 20, and 9:06 am, Friday, roughly an 11-hour period.

The earthquakes ranged from magnitude 0.9 to 2.3 and “occurred at depths of 12 to 15 kilometers beneath the summit crater” of Kanlaon.

The increased seismic activity “indicates that fracturing at deeper levels is occurring and may possibly lead to further unrest,” Phivolcs said.

So far, Kanlaon remains under Alert Level 1. But the volcano could be raised to Alert Level 2 if the spike in activity persists.

As for other parameters, Phivolcs noted that sulfur dioxide emission averaged 786 tons per day last Tuesday, July 18, “slightly higher” than the average emission of 566 tons per day since March.

Kanlaon’s middle slopes have also been showing inflation or swelling since March.

Phivolcs advised the public not to enter the 4-kilometer-radius permanent danger zone around the volcano “due to increased chances of sudden and hazardous phreatic eruptions occurring without warning.” – Rappler.com