• GILBERT P. BAYORAN
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported a brief minor explosion at the summit of Kanlaon Volcano at about 3:11 p.m. of February 6.
The eruption, which lasted two minutes, generated a poorly visible plume that rose 600 meters above the vent, before drifting southwest, scattering thin ashfall over Sto. Mercedes and San Luis, Barangay Sag-ang, La Castellana in Negros Occidental, PHIVOLCS said.
The explosion generated an airwave that was recorded at 70 Pascals five kilometers east of the summit crater and heard as a booming sound in Brgy. Yubo, La Carlota City and Brgy. Sag-ang, La Castellana, Negros Occidental, it added.
Muddy stream flow was observed at Buhangin River in Brgy. Sag-ang, Robles to Lalagsan, in La Castellana, heading towards Moises Padilla and flowing into the Binalbagan River.
Sulfurous fumes were also reported in several barangays of La Castellana, according to PHIVOLCS.
Prior to the event, Phivolcs said the sulfur dioxide (SO2) flux was measured at an average of 2,249 tons a day, a significant drop from the medium-term average of 4,484 tons/day since June 3 last year, while the degassing from the summit crater has been weak since the previous evening.
Phivolcs also noted that the upper to middle slopes of the volcano edifice have been undergoing inflation or swelling since January 10 this year.
When occasional plugging of the volcanic conduit occurs and SO2 emission and degassing weakens, the resulting pressure build-up within the conduit could trigger explosions such as the minor eruption yesterday, it added.
This means that the magmatic eruption that occurred may be followed by similar short-lived explosive eruptions in the short term which may generate pyroclastic density currents (PDC) within the 6-kilometer radius area on the summit, PHIVOLCS said.
Alert Level 3 remains hoisted over Kanlaon volcano.*
