If unrest at Kanlaon Volcano continues it could trigger a magmatic eruption with lava flow likely to hit four cities and two towns in Negros Island, a Philippine Institute of Volcanology and Seismology (Phivolcs) hazard map shows.
The Phivolcs’ Kanlaon Volcano Lava Flow Hazard Map identifies mostly upland barangays of Canlaon City in Negros Oriental, and La Castellana, Bago City, La Carlota City, Murcia and San Carlos City as areas likely to be hit.
Kanlaon Volcano had 79 volcanic earthquakes and emitted 11,558 tons of sulfur dioxide from 12 a.m. Wednesday to 12 a.m. Thursday, the Phivolcs reported.
Pearly Sianson, Phivolcs science research specialist, said a magmatic explosion could cause Kanlaon to spew lava or molten rocks.
Magmatic eruptions could be effusive or explosive, she said.
Effusive eruptions means the passive emission of lava, while explosive eruptions are dominated by eruption of fragmental material, Sianson said.
If ground deformation increases it means that magma is rising toward the crater, she said.
The last magmatic explosion at Kanlaon was in 1902.
The activity level at Kanlaon has remained high, and we are advising the public to prepare, Mari Andylene Quintia, resident volcanologist at the Kanlaon Volcano Observatory, said.
“If the trend continues and intensifies, we may raise the alert level (at Kanlaon) to 3,” she said, which means the Permanent Danger Zone will be increased from 4 to 6 kilometers that would require more residents to evacuate.
Compared to phreatic eruptions, which are steam-driven explosions without magma, magmatic eruptions are more dangerous, Quintia said.
A magmatic eruption is more lethal and affects a larger area, she said.
They are keeping track of three volcanic parameters: volcanic earthquakes, SO2 emissions, and ground deformation. If there is a sudden increase in these parameters, it could signal an impending eruption, she said.*