• GILBERT P. BAYORAN
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) yesterday issued a warning that heavy to intense rainfall in Negros Island may generate volcanic sediment flows, or lahar, or muddy run-off and related siltation in rivers and drainage areas of Kanlaon Volcano.
Signal No. 1 has been raised in Negros Occidental due to Tropical Depression Verbena.
Communities of Bago City, La Castellana, La Carlota, Moises Padilla and San Carlos City in Negros Occidental, and Canlaon City in Negros Oriental that are situated along the 17 rivers and creeks maybe affected by lahar and sediment laden stream flows and related flooding, as well as siltation, according to PHIVOLCS.
Post-eruption lahar can be generated by intense rainfall eroding loose material from remnant pyroclastic density current (PDC) deposits of the October 24 explosive eruption and loose ashfall from it, as well as recent ash emission events, it added.
In addition, non-eruption lahar can be generated when areas of the upper slopes that have been recently exposed by landslides, or weakened during the passage of Typhoon Tino early this month, become susceptible to failure and feed debris that have already delivered destructive flows to downstream communities, PHIVOLCS said.*
