BACOLOD City – The Philippine Institute of Volcanology and Seismology (Phivolcs) has again observed increased volcanic activity at Kanlaon volcano. Localized earthquakes on the northwest flank of the mountain have been recorded.
Phivolcs director Renato Solidum Jr. said the localized earthquakes monitored were high frequency volcanic tremors.
Compared to tectonic quakes which are caused by fault movements, a volcanic earthquake is caused by movements or eruptions of magma from the volcano.
“The series of earthquakes is clustered in the northwestern flanks of the volcano and needs to be monitored,” said Solidum.
Kanlaon volcano straddles the border shared by Negros Oriental and Negros Occidental. At 2,465 meters above sea level, it is the highest point in Negros Island and in the Visayas.
In an advisory, Phivolcs said the localized earthquake activity on the lower northwest flank of Kanlaon Volcano, in the jurisdiction of Bago City, Negros Occidental, began since 8:12 p.m. on Feb. 8.
As of 9 a.m. on Wednesday, Feb. 9, Phivolcs recorded 11 “very shallow” earthquakes with magnitudes 0.9 to 2.1.
Sulfur dioxide (SO2) emission from the summit crater remains within baseline levels, according to Phivolcs, averaging 387 tons per day since October 2021.
On Feb. 3, the SO2 emission was 138 tons. There was no visible degassing activity from the crater on Feb. 9.
“Overall, localized shallow seismic activity and short-term ground deformation are likely caused by shallow hydrothermal or geothermal processes beneath the edifice that could generate phreatic or steam-driven explosions,” the advisory read.
Kanlaon, part of the Negros Volcanic Belt, is a large stratovolcano dotted with numerous flank cones and craters, many of which contain lakes. The volcano is the most active in Central Visayas.
Kanlaon volcano remains under alert level 1 (low level unrest).
Phivolcs reiterated that entry into the four-kilometer radius permanent danger zone (PDZ) must be strictly prohibited due to the further possibilities of sudden and hazardous steam-driven or phreatic eruptions.
In addition, residents on the lower slopes of Kanlaon are advised to report any unusual observations to their local officials, or to the Kanlaon Volcano Observatory in La Carlota City, Negros Occidental.
Pilots are likewise advised to avoid flying close to the volcano’s summit, as ejecta from any sudden phreatic eruption can be hazardous to aircraft. (With a report from the Philippine News Agency/PN)
