BACOLOD City – Residents of Hacienda Caridad, Purok 5, Barangay Baliwagan, San Enrique, Negros Occidental were surprised when a portion of the Candaguit River suddenly swelled.
In a radio interview over the weekend, Rex Nebril and Ernesto Suanico, all of Purok Malipayon, Barangay Sibucao, said they were fishing in the river when a slight tremor suddenly occurred.
Both witnesses also said that they heard a loud growling noise just 50 meters from their position and initially thought that it was just a large animal taking a dip in the river.
But when the two decided to approach the area where they heard the noise, they discovered that a portion of the river bed has risen by three feet with the bulge 35 meters long.
The two also claimed to have seen smoke coming out of the crack.
Bacolod City Disaster Risk Reduction and Management Office (CDRRMO) head Joemarie Vargas said the sudden rise in the river bed may have been caused by the buildup of either nitrous oxide or methane gas.
Vargas said nitrous oxide gas has the same odor as rotten eggs and it is possible that a large tree may have been swept in the area and was eventually buried beneath the river then rotted.
The gas built up after years of decomposition until the pressure eventually triggered the river bed to rise up.
“It’s just like what you see with buried garbage in which if you bury it for too long it would eventually create methane gas,” Vargas said. “However since this was located in the marshland then it is most likely to be nitrous oxide.”
Vargas said such incidents are normal and people need not to be alarmed, although he advised San Enrique officials to prevent anyone from swimming in the area because it is possible that there is still a pocket of gas underneath which could collapse and create a larger hole.
He added that town officials should consult geologists and survey the area
He also assured that the incident was not connected to the restive Mt. Kanlaon which is presently under Alert Level 2 status.