The Philippine Institute of Volcanology and Seismology (Phivolcs) warned the public against entering the four-kilometer permanent danger zone (PDZ) around Kanlaon Volcano in Negros Island following the increased seismic activities since Monday, September 4.
In an advisory, Phivolcs said 36 volcanic earthquakes, 34 of which are volcano-tectonic, were recorded from 5:00 a.m. of September 4 to 7:00 a.m. of September 6.
In an interview with the Philippine News Agency, Phivolcs director Teresito Bacolcol said the average volcano-tectonic earthquakes in Kanlaon from August 1 to September 3 is two to three per day.
“This [increase in seismic activity] means there is fracturing of rocks beneath the volcano. As magma rises to the surface, it puts stress on the surrounding rocks, leading to their fracturing,” he said.
Compared to low-frequency volcanic earthquakes that are purely produced by the movement of magma toward the volcano’s surface.
Bacolcol said volcano-tectonic earthquakes are produced by both the movement of magma as well as the breaking or fracturing of rocks.
Despite this development, Phivolcs said Alert Level 1 remains up over Kanlaon.
“Should the above uptrend in monitoring parameters persist, the volcano status may be raised to Alert Level 2 to warn of increasing unrest,” it said.
The agency, however, warned the public from entering the PDZ “due to increased chances of sudden and hazardous phreatic eruptions occurring without warning.”
“Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ejecta from any sudden phreatic eruption can be hazardous to aircraft. DOST-PHIVOLCS is closely monitoring Kanlaon Volcano’s activity and any new development will be relayed to all concerned,” it added. (PNA)