Tunnel found under landslide-hit village

A hole that resembles the structure of a tunnel was found 22 meters beneath the ground in the landslide-hit barangay of Sirao in upland Cebu City.

This is the reason why disaster officials have urged nearby residents to vacate the spot to prevent untoward incidents.

Harold Alcontin, operations chief of the Cebu City Disaster Risk Reduction Management Office, said the soil in the upland barangay continues to move because of the hole on the ground.

The soil, he said, is gradually caving in despite the absence of rainfall.

“Bisan dili ting-ulan, nagsige pa gihapon og move ang yuta,” he said at a radiolive forum dubbed “Kapihan sa PIA” organized by the Philippine Information Agency-Cebu.

The tunnel was recently discovered by the personnel of the Mines and Geosciences Bureau (MGB) Central Office following an area inspection.

MGB used its ground penetrating radar (GPR), an electromagnetic technique useful for ground subsidence and sinkhole detection.

“According to MGB report after they used the ground penetrating radar (GPR), they discovered a subsidence hazard… Naay tunnel sa ilawom nga nihulpa. Its 22 meters below the surface nga mura’g agianan og tubig,” Alcontin said.

He said the residents are advised to vacate the area because the continuous movement of the earth and landslides might cause further damage and accidents.

“Karon nakit-an nga ni-slide siya padulong sa residents. Naghatag na mi warning sa tawo since the area is unsuitable for habitation. It’s a no build zone,” he said.

At present, he said at least 15 households or 25 families have already relocated to a safer area.

He said the Department of Social Welfare and Services (DSWS) had conducted profiling of the affected families, while the Division for the Welfare of the Urban Poor (DWUP) is assisting them for possible relocation. One of the identified relocation sites is Barangay Guba.

Barangay Sirao has been identified as highly susceptible to landslide due to its soil composition. According to local state geologists, Sirao’s lithology is a combination of sandy and clayey and weathered bedrock, thus it is typical that a mass movement will occur.

Alcontin said areas declared as highly susceptible to subsidence and landslide should be free from permanent habitation.

He said Barangay Sirao has history about series of ground movements since 1997 that is why the locality is under constant monitoring.

Through GPR survey, layering in soils and rocks can be mapped and underground objects and voids can be detected.

The MGB’s GPR surveys are focused on areas experiencing rapid growth and development and/or envisioned for development.

Specific areas where GPR survey is conducted are evacuation centers, settlement sites, and economic zones in karst areas that are prone to land subsidence due to sinkhole collapse.