Kanlaon restive; Alert Level 2 eyed

The alert level at Kanlaon Volcano on Negros Island may be raised to Level 2 after amid increased seismic activity, including gas emissions, the Philippine Institute of Volcanology and Seismology or Phivolcs said on Wednesday.

Kanlaon has been showing signs of unrest after 15 volcano-tectonic earthquakes were recorded between 3:58 a.m. and 5 a.m. on 22 November.

Phivolcs said Alert Level 1 remains on Kanlaon, but this may be raised to Alert Level 2 should the unrest increase.

"The public is reminded that Alert Level 1 prevails 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," Phivolcs said in its latest advisory.

It noted that the earthquakes ranged in energy from magnitude 1.4 to magnitude 4.2 and occurred at depths of 0 to 2 kilometers beneath the northern flank of the Kanlaon range.

In its current condition, the volcano may emit sudden steam-driven explosions or phreatic eruptions as its emission of volcanic sulfur dioxide or SO2 from the summit crater has increased since 18 July — averaging 570 tons daily since 1 May, with the latest SO2 measurement on 14 November averaging 1,017 tons daily.

Phivolcs said the ongoing volcano-tectonic earthquake activities indicate that fracturing at more profound levels is occurring and may possibly lead to further unrest.

The monitoring parameters in the past months have been consistent with shallow hydrothermal activity driven by degassing of deeper magma. In contrast, the ongoing volcanic-tectonic earthquake activity indicates shallow rock-fracturing on the edifice, which may lead to further unrest.

Kanlaon remains at low-level unrest wherein a slight increase in volcanic earthquake and steam or gas activity has been observed, with volcanic plume emission logged at 200 meters moderately drifting southeast.

Phivolcs said the ground deformation data from continuous GPS and electronic tilt measurements have recorded shorter-term inflation of the southwestern middle slopes since last October and longer-term inflation of the entire edifice since March 2022.

It also strongly advised the public and local government units to be vigilant.

Entering a four-kilometer permanent danger zone near the volcano remains prohibited due to increased chances of sudden and hazardous phreatic eruptions occurring without warning.

Flying aircraft close to the volcano is likewise not allowed due to increased chances of sudden and hazardous phreatic eruptions occurring without warning.

Lade Jean Kabagani@tribunephl_Lade