• GILBERT P. BAYORAN
The Philippine Institute of Volcanology and Seismology (Phivolcs) reported yesterday an increase in seismic activity at the Kanlaon Volcano in Negros Island.
Phivolcs monitored 35 volcano-tectonic earthquakes from 10 p.m. Thursday to 9:06 a.m. Friday. These earthquakes, ranging from magnitudes 0.9 to 2.3, were 12 to 15 kilometers deep beneath the summit crater.
Volcano-tectonic earthquakes occur near or beneath volcanoes. These are produced when rocks beneath or around the volcano move due to pressure from magma.
Based on the Phivolcs’ advisory, the ongoing seismic activity indicates that fracturing at deeper levels is occurring, and may possibly lead to further unrest.
It added that a slight increase in sulfur dioxide (S02) emission, and short-term inflation (bulging) of the slopes of Kanlaon have also been observed.
Negrenses were reminded that Alert Level 1 prevails over Kanlaon.
Should the above uptrend in monitoring parameters persist, the volcano’s status may be raised to Alert Level 2 to warn of increasing unrest, Phivolcs added.
It also strongly advised the public and local government units to be vigilant and refrain from entering the four kilometer Permanent Danger Zone (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.*