Phivolcs keeps tight watch over Kanlaon amid quakes

Government volcanologists are closely watching Mt. Kanlaon on Negros Island after a series of volcanic earthquakes had shaken the area since Sunday afternoon.

In its bulletin on Monday morning, the Philippine Institute of Volcanology and Seismology (Phivolcs) said 136 volcano-tectonic earthquakes were recorded on Kanlaon’s western flanks over 24 hours.

According to the Philippine Seismic Network, four quakes occurred between 1:01 a.m. and 2:06 a.m. on Monday, with magnitudes ranging from 3.2 to 4.7. These were felt in La Carlota and Bago cities in Negros Occidental province, as well as in Canlaon City in Negros Oriental province.

White steam plumes were rising 200 meters from the crater, Phivolcs said.

Sulfur dioxide emission was measured at an average of 438 tons per day on June 13. This gas separates from magma as it comes closer to the surface, volcanologists explained.Mariton Bornas, chief of Phivolcs’ volcano monitoring and eruption prediction division, said the agency would not speculate whether Kanlaon would soon erupt, but it would remain vigilant for significant changes in the volcano’s activity.Preparation

“The series of earthquakes can be related to ground deformation related to regional stresses, or hydrothermal processes commonly operating beneath active volcanoes,” Bornas told the Inquirer.

“What we need to do is to remain prepared and for local government units to revisit their contingency plans due to these events,” she added.

Kanlaon was placed on alert level 1 in March, meaning it had entered a period of unrest. Phivolcs reminded local governments and the public that entry into the 4-kilometer permanent danger zone (PDZ) was prohibited due to potential sudden and hazardous steam-driven eruptions.

According to Bornas, a village called Araal sits on the western flank of Kanlaon but its settlements are outside the PDZ. “However, on the other sides, like in the south and southeast—La Castellana and Canlaon—settlement and farming have already encroached into the PDZ,” she said. “In any case, potential hazards can extend many kilometers away from the central vent.”

Phivolcs said civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as materials spewed from any sudden phreatic (steam-driven) eruption posed aviation risks.

Highest point

Kanlaon is located at the borders of Negros Oriental and Negros Occidental. At 2,465 meters above sea level, it is the highest point on Negros Island and in the Visayas.

According to Negros Occidental provincial administrator Rayfrando Diaz, local officials are hoping that “these are just minor volcanic activities,” especially now that the province is dealing with a public health crisis due to the coronavirus pandemic.

“We are praying Negros Occidental will be spared from such a situation,” he said.

Diaz said representatives from the Provincial Disaster Risk Reduction and Management Office, Phivolcs and the towns and cities around the volcano met on Monday to discuss measures to enhance preparedness.Phivolcs records showed that Kanlaon, one of the most active volcanoes in the Pacific Ring of Fire, last erupted in March 2016, producing a plume that stretched 1,500 m above the crater and a “booming sound” heard in villages nearby. —REPORTS FROM JHESSET O. ENANO, RAFFY CABRISTANTE AND CARLA GOMEZ INQ