Geologist: Sinkholes should be off-limits

CEBU, Philippines — Former Mines and Geosciences Bureau (MGB) chief geologist Liza Socorro Manzano has issued another strong public warning following the emergence of multiple sinkholes in Tabogon, Cebu, after the recent 6.9-magnitude earthquake.

Manzano described the formations as “amazing but dangerous,” stressing that the areas should be off-limits to curious onlookers or “usiseros.”

She noted visible landslide scars, slump features, and escarpments surrounding the sinkhole sites, suggesting that the earthquake may have damaged the cave system beneath and diverted underground river flow.

According to Manzano, strong aftershocks or heavy rainfall could trigger further collapses and landslides. She also expressed concern for the safety of geologists conducting field assessments, saying that even trained personnel face risks due to the unstable terrain.

Manzano observed the spalling of sandy materials in close-up images of the sinkhole, likening its shape to an hourglass.

The Tabogon Municipal Disaster Risk Reduction and Management Office (MDRRMO) confirmed sinkhole formations in Purok Andres, Barangay Canao-Canao; along the shoreline of Barangay Maslog; and in Sitio Manaybanay, Barangay Maslog.

The Philippine Coast Guard has begun deploying buoys to restrict access to affected coastal areas. Meanwhile, the local government unit (LGU) has relocated municipal operations after the Executive Building was declared unsafe. The LGU continues to coordinate with barangay officials for signage installation and public advisories.

Residents are urged to avoid sinkhole sites, report ground cracks or unusual water movement, and strictly follow safety protocols.

Manzano’s previous warnings—and those of the MGB—about the vulnerability of karst terrain, particularly in limestone-rich areas, underscore the unpredictable nature of sinkhole unroofing and the importance of proactive risk management.