Phivolcs Warns of Kanlaon Lahar Threat Amid Rains

By Glazyl M. Jopson

BACOLOD CITY – The Philippine Institute of Volcanology and Seismology has warned of possible lahar flows near Kanlaon Volcano due to continued rains.

In a Facebook post, the local government of La Castellana, Negros Occidental—severely affected by the June 3, 2024 eruption—alerted the public to mudflows from volcanic ash washed away by rains in Sitio San Luis, Barangay Sag-ang.

The ash-laden flow reached the Bungahin River, also in La Castellana, on Friday, June 6.

Similar lahar activity was reported in Sitio Tamburong, Barangay Biak na Bato.

In its June 6 advisory, Phivolcs cited data from the Philippine Atmospheric, Geophysical and Astronomical Services Administration showing that Negros Island is experiencing effects of a low pressure area and the southwest monsoon.

Heavy rains caused cohesive, cement-like lahars along Buhangin River and beneath Hacienda 92 Bridge in Barangay Sag-ang, as well as in Ibid Creek in Barangay Biak na Bato.

Rainfall recorded by the Kanlaon Volcano Observatory’s all-weather station in La Carlota City totaled 45.5 mm over 3.5 hours, with likely higher volumes near the summit.

Phivolcs said the southwest monsoon could bring intermittent heavy rains over Negros Island in the coming months, increasing the risk of lahars.

These may trigger muddy streamflows or runoff in rivers draining the southern slopes of Kanlaon, especially in areas already impacted by earlier lahars.

Lahars can pose serious threats, including flooding, burial of structures, and destruction of communities along the volcano’s middle and lower slopes.

Last month, heavy rains triggered ash deposits to flow from creeks, blocking a bridge and the Biak na Bato Highway and prompting a temporary road closure in La Castellana.

Phivolcs urged heightened vigilance and preparedness among communities along rivers near southern Kanlaon.

It also advised local government units and residents to closely monitor weather conditions and implement preemptive measures when heavy rainfall is forecast or has started over Kanlaon’s upper slopes.

Rains remain the only early warning for potential lahars.