Heavy lahar flow from Kanlaon Volcano that made the highway in Barangay Biak na Bato, La Castellana, Negros Occidental, impassable also caused the forced evacuation of residents Wednesday afternoon, July 5, Mayor Rhummyla Nicor Mangilimutan said.
The muddy flow was triggered by strong rain that washed out volcanic debris, which included ash, spewed by Kanlaon during its eruption Monday, said Mari-Andylene Quintia of the Philippine Institute of Volcanology and Seismology (Phivolcs) Kanlaon Observation Station in La Carlota City.
Mangilimutan said there was heavy presence of lahar in Biak na Bato and in some areas in barangays Masulog and Cabagna-an.
She ordered the evacuation of residents in six sitios in Biak na Bato and one in Masulog, the mayor said.
The evacuation was ordered because if heavy rains cause more lahar flow at night it would be extremely difficult to rescue trapped residents, she said.
She said there was also lahar flow in Upper Mananawin in Barangay Masulog.
Lahar was also seen flowing down the Baji Baji falls in Barangay Cabacungan, La Castellana, Barangay Captain Marvin Escander said.
Thunderstorms Wednesday afternoon generated volcanic sediment flows or lahar on the southern slopes that were detected by three seismic stations of the Kanlaon Volcano Network (KVN), Phivolcs reported last night.
These lahars began approximately around 1 p.m. and lasted 25 minutes based on the seismic record, it said.
Grey cohesive mud, plant debris and gravel have been deposited by lahars in at least four waterways: Tamburong Creek, which courses through Biak-na-bato and Calapnagan, La Castellana; Intiguiwan River in Guinpanaan and upstream Baji-Baji Falls in Cabacungan, La Castellana; Padudusan Falls, Masulog, Canlaon City; and the Binalbagan River, which drains the southern flank of Kanlaon Volcano, it said
The lahars were generally channel-confined, but flows along Tamburong Creek overflowed and dumped a few centimeters of deposit on a stretch of the main road in Biak-na-Bato, rendering this impassable to motorists, Phivolcs said.
The Philippine Atmospheric Geophysical and Astronomical Services Administration forecasts thunderstorms June 6 and 7 that could generate larger volume lahars, it said.
Phivolcs strongly recommends increased vigilance and readiness of communities along rivers draining southern Kanlaon.
These communities and local government units are advised to continually monitor weather conditions and take pre-emptive response measures for their safety from potential lahars, it said.*