A total of 62 volcano-tectonic (VT) earthquakes were recorded at Kanlaon Volcano from 12 a.m. to 7:30 p.m. Wednesday, Jan. 14, prompting the Philippine Institute of Volcanology and Seismology (Phivolcs) to issue a notice of increased seismic activity and to advise the public to stay vigilant.
Mari-Andylene Quintia, Phivolcs resident volcanologist at the Mt. Kanlaon Observatory in La Carlota City, noted that these seismic events ranged in strength between ML 0.6 and ML 3.9 and were generated at depths of 0 to 13 kilometers beneath the northwestern flanks of the volcanic edifice.
The strongest of these events were felt at Intensities I to IV in La Carlota City, Bago City and Bacolod City in Negros Occidental, as well as in Canlaon City, Negros Oriental, Quintia said.
Quintia explained that VT earthquakes are generated by rock-fracturing processes, and this surge in activity strongly indicates progressive fracturing beneath the volcano as rising magma or magmatic gas drives a path toward the surface.
Volcanic sulfur dioxide (SO2) gas emissions from the summit crater of Kanlaon averaged 1,248 tons on Tuesday, near the medium-term average of 1,767 tons per day since January 1. It was at 4,126 tons on January 9, a Phivolcs advisory said.
The overall parameters indicate that renewed magma intrusion is taking place beneath the edifice which could potentially lead to a moderately explosive eruption, it said.
The public is reminded that Alert Level 2 prevails over Kanlaon, which means that the volcano is in a state of increased unrest, the Phivolcs advisory said.
The increase in VT events could lead to increased chances of steam-driven or phreatic eruptions or short-lived weak to moderately explosive eruptions occurring at the summit that could generate life-threatening volcanic hazards such as pyroclastic density currents or PDCs, ballistic projectiles, ashfall, rockfall and others, it said.
Phivolcs strongly recommended that communities within the 4-km Permanent Danger Zone or PDZ strictly remain evacuated and those within the 6-km radius from the summit crater be vigilant and ready in case unrest worsens.
In addition, increased vigilance against potential syn-eruption lahars and sediment-laden streamflows in channels draining the edifice is strongly advised should intense rains occur during eruptive unrest, Phivolcs said.
Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden eruption can be hazardous to aircraft, it said.*