MGB: Fence off sinkhole area

CEBU, Philippines - The Mines and Geosciences Bureau-7 upheld their earlier recommendations on the immediate installation of a permanent fence, continuous monitoring of the ground subsidence and proper signage or warning around the Dumanjug sinkhole.

This came after Senior Science Research Specialist Abraham Lucero Jr. conducted a site assessment of the sinkhole in Sitio Plaza, Barangay Camboang, in Dumanjug, Cebu.

The sinkhole, which measures 10 meters by 8.5 meters with a depth of three to four meters, is just 11 meters from the barangay road.

MGB-7 regional director Loreto Alburo said they issued a landslide threat advisory on the findings and recommendations which were addressed to and received by Barangay Captain Meliza Mae Quirante of Barangay Camboang and Dumanjug Mayor Nelson Garcia.

The advisory, he said, emphasized the threat of ground subsidence.

A sinkhole is a natural depression or hole in the surface topography caused by Karst processes – the chemical dissolution of carbonate rocks.

Alburo also said they found out that the affected area has an indication of an existing subterranean river system or a water channel.

He added that the collapse or cave-in of the cave roof which resulted to the formation of a sinkhole was attributed due to the 6.9 magnitude earthquake and many aftershocks, and intense and prolonged rain.

Alburo explained that sinkholes are common where the rock below the land surface is limestone, carbonate rock, rocks that can naturally be dissolved by circulating groundwater. As the rock dissolves, spaces and caverns develop underground.

These sinkholes can be dramatic because the surface land usually stays intact until there is not enough support. Then a sudden collapse of the land surface can occur.

“We urge our local officials to report immediately to the MGB-7 if there are occurrences of sinkhole formations and to continuously monitor such sinkhole to avoid further damage to lives and properties,” Alburo added.

The communities are also reminded to be vigilant and to avoid settlement near the affected area. – (FREEMAN)