Phivolcs: Watch out for Mayon, Kanlaon lahar as Ada triggers rain

MANILA, Philippines – The Philippine Institute of Volcanology and Seismology (Phivolcs) on Friday, January 16, warned residents living near Mayon Volcano in Albay and Kanlaon Volcano in Negros Island to be on alert for possible lahar flows, as Tropical Storm Ada (Nokaen) triggers rain.

Albay is facing moderate to intense rain due to Ada in the next 48 hours, based on the rainfall outlook of the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA).

The rain in Albay might mix with volcanic debris and “generate volcanic sediment flows or lahars, muddy streamflows, or muddy run-off in rivers and drainage areas of Mayon Volcano,” Phivolcs said in an advisory.

Mayon Volcano was raised to Alert Level 3 last January 6 due to a magmatic eruption. Unrest has remained intensified since then, with lava flows, rockfall, and pyroclastic density currents (PDCs) observed on the volcano’s slopes.

PDCs are made up of fragmented volcanic particles, gases, and ash that travel down volcanic slopes at high speeds. They can destroy or burn anything in their path, with temperatures generally ranging between 200°C and 700°C, according to the United States Geological Survey.

New PDC deposits along the Mi-isi, Bonga, and Basud gullies may lead to hot lahar flows which “could cause scalding upon contact” and lead to “serious and life-threatening injuries,” Phivolcs warned the public.

The following areas in Albay are at risk:

Daraga

• Mi-isi Channel
• Binaan Channel

Legazpi City

• Mabinit
• Bonga
• Matanag
• Buyuan
• Padang

Santo Domingo

• Lidong River
• Basud River

Guinobatan

• Masarawag Channel
• Maninila Channel
• Related distributary channels

Negros risks

Compared to Albay, Negros Island is not as heavily affected by Ada, but it is still seeing scattered rain and thunderstorms due to the tropical storm.

The rain in Negros Island, which can be heavy at times, may mix with “loose material” from PDC deposits generated by Kanlaon Volcano’s recent explosive eruptions, or mix with previously emitted ash. The volcano has been under Alert Level 2 since July 29, 2025.

“Prolonged heavy rainfall could generate life-threatening lahars and sediment-laden streamflows on major channels draining the southern, western, and eastern slopes of Kanlaon Volcano,” Phivolcs said.

Areas on the volcano’s upper slopes “that have been recently exposed by landslides or weakened” during the onslaught of Typhoon Tino (Kalmaegi) in November 2025 may also “feed debris to rivers that have already delivered destructive flows to downstream communities.”

“Kanlaon lahars, which were shown by [Tino] to be strong enough to transport enormous volumes of gravel and boulders, could threaten communities,” added Phivolcs.

Residents of Bago City, La Carlota City, La Castellana, Moises Padilla, and San Carlos City in Negros Occidental, as well as Canlaon City in Negros Oriental, located along the following rivers and creeks are at risk:

• Ibid River
• Cotcot River
• Talaptapan River
• Malaiba River
• Panubigan Creek
• Buhangin–Indurayan River
• Najalin River
• Inyawan River
• Maragandang River
• Panun-an Creek
• Intiguiwan River
• Camansi River 
• Maao River 
• Tokon-tokon River
• Masulog River
• Binalbagan River
• Taco Creek
• Linothangan River

Phivolcs advised affected communities both in Albay and Negros Island to regularly monitor weather conditions, avoid the abovementioned waterways, and follow authorities’ instructions, including preemptive evacuation, if necessary. – Rappler.com