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Sinkholes in South Florida

Expert says it's rare that sinkholes form without warning

MIAMI – It's rare when sinkholes claim lives, but these geological events are common in Florida. However, Dr. Shimon Wdowinski, a geology professor at the University of Miami said South Florida is at less risk than other parts of the state.

"Here in the Tri County, there is a very small chance of that," Wdowinski told Local 10's Roger Lohse.

Wdowinski said the sinkholes that make news in South Florida are usually made man. Most occur from water main breaks that erode the foundation of a road or someone's property.

It was basically the same dynamic at work in Seffner last week but on a much larger scale.

Wdowinski explained that Florida lies on bedrock made of limestone that can be eaten away by acidic groundwater, like rain run off.

The resulting erosion creates voids in the limestone that can collapse when the rock can no longer support the weight of what's above it.

"And at some point the layer on top of that loses its strength and basically collapses into the cavity," Wdowinski said.

Though it has happened, true sinkholes are pretty rare in South Florida. That's because the cavities in the limestone where they form, are much deeper underground.

"Near Tampa it's near the surface. That's why they suffer from these sinkholes," Wdowinski said.

A map of the sinkholes in Florida over the past 60 years provided by the Department of Environmental Protection show most of them have happened in the west central part of the state. But just like hurricanes and tornados in Florida, sinkholes come with the territory.

"If there's a cavity underneath your house, is there anything you can do?" asked Lohse.

"Not really," replied Wdowinski who also said it's rare that a sinkhole will form without warning.  Usually a homeowner will notice cracks developing in the walls or a depression that forms in the yard and have plenty of time to evacuate.