Following the Magnitude 6.9 earthquake in Northern Cebu, the Mines and Geosciences Bureau (MGB) conducted a sinkhole inventory in the municipalities of San Remigio and Daanbantayan. These new sinkholes give us a rare glimpse into what lies beneath the ground surface.

Sinkholes, particularly those of the cover-collapse type, form when the ground surface suddenly collapses into underlying voids or cavities. This process can expose caves, which are often part of a larger, interconnected subsurface network. When a sinkhole forms above an aquifer containing water, it is referred to as a cenote, which exposes a deep depression filled with clear, turquoise blue water. The groundwater in these aquifers often resurfaces as karst springs, providing a vital source of water for local communities.

Sinkholes act as natural recharge points for groundwater, allowing surface water to flow into the subsurface. However, because infiltration through sinkholes occurs rapidly, pollutants can easily enter and spread through underground aquifers. This makes karst systems highly vulnerable to contamination. In simple terms, sinkholes aren’t bottomless pits, they’re direct pipelines to the water we use regularly. Throwing trash into them is like pouring waste directly into your own water supply. The contamination of the groundwater poses severe health risks to the communities. Local officials should impose stricter measures that would keep the environment and groundwater in the sinkholes clean.

Cover-collapse sinkhole in Daanbantayan

Cenote in San Remigio

Karst spring in Tuburan