Authorities have warned residents in northern Cebu to stay alert for sinkholes and widening ground cracks following the 6.9-magnitude earthquake that struck the province on Sept. 30, as experts caution that ground subsidence could worsen without proper safety measures.
The Mines and Geosciences Bureau in Central Visayas (MGB-7) said the quake has destabilized soil in several municipalities and cities, prompting the agency to issue a Subsidence Threat Advisory covering San Remigio, Medellin, Bogo City, Tabogon, and Daanbantayan — areas now classified as high-risk zones.
“The recent seismic activity has destabilized ground conditions, resulting in the formation of sinkholes in certain affected areas,” the bureau said. “Ground cracks and depressions were also noted nearby, indicating potential progression of the subsidence.”
Local governments were told to cordon off sinkhole-prone sites, install warning signs, and bar residents from entering hazardous areas. The bureau also warned against backfilling or covering sinkholes without proper geotechnical assessment, especially in areas with underground rivers that could trigger further collapses or flooding.
Two technical teams have been deployed to conduct field validation and collect data for a comprehensive geohazard assessment report, the MGB said.
In Medellin, all barangays with confirmed sinkholes have been classified under a high subsidence hazard rating. Similar advisories were sent to neighboring towns.
San Remigio Mayor Mariano Martinez said the municipality had recorded more than 100 sinkholes even before the earthquake, with 15 new ones emerging after the tremor.
Hundreds of residents have been evacuated from Sitio Sansan in Barangay Maño, where some cavities were large enough to swallow trees, boats, and parts of houses. Martinez said several sinkholes were filled with underground water, weakening the soil further and raising the risk of collapse.
Families living near the largest cavities have been relocated while structural inspections continue for schools and public buildings in Hagnaya and surrounding barangays.
The MGB urged residents to immediately report new cracks or sinkholes and avoid rebuilding in unstable zones. It added that continuous monitoring, proper information dissemination, and strict adherence to geohazard warnings are critical to ensuring public safety amid ongoing aftershocks and heavy rains.
A final geohazard report will guide local governments in designing mitigation and relocation programs for affected communities, the bureau said.
Cebu Business News
