John Lorca, coordinator of a technical working group (TWG) tasked to oversee the
critical crater-lake, said they implemented a continuous watch of the lake by activating the monitoring station in Barangay Salacafe, T’boli.
Last month, he said, the lake's water level was monitored to have decreased by at least one centimeter (cm).
But a recent earthquake triggered a landslide on the northwestern side of the lake causing the dumping of an estimated 180,000 cubic meters of pyroclastic materials directly into the lake, he said.
Lorca said this caused the water level to increase from negative -1 cm to 5 cm or an
increase of 6 cm.
He said their latest monitoring showed that the water level dropped by 2.5 cm from 5 cm.
During an ocular inspection, he said, they discovered the damming of water at a certain portion of Ga-ao River due to the landslide.
He said they found that the natural sluicing of pyroclastic materials and the damming
in the waterways caused the normal rise and fall of water levels in the lake.
Lorca assured they will continuously monitor activities in the area to prevent any
He said they would also conduct a clean-up on the outlet of the crater-lake to allow the normal flow of water to its tributaries downstream.
“We ask the Philippine Institute of Volcanology and Seismology to conduct an in-depth investigation to determine if the changes in the water level and the presence of the pyroclastic materials will affect the safety of the communities near the lake and its ecological system,” he added.
Two major disasters have occurred in a decade: the Lake Maughan tragedy and the flooding of the Allah River due to an earthquake.
In September 1995, one of the lake’s walls collapsed, causing a huge volume of water to overflow towards the Allah River. The incident left at least 80 people dead.
In 2002, an earthquake caused the lake’s water to overflow, causing another major
flashflood at the Allah River.
These incidents affected around 23,786 families and an estimated P515 million worth of damages to crops and infrastructure.