An Overview of Florida Sinkholes: Types and Causes

June 15, 2011

Florida has more sinkholes than any other region in the U.S. Sinkholes are caused when the ground beneath the surface is made of certain types of rock, such as limestone, that can be dissolved by water. When water circulates through these rocks under the ground, dissolving them, and washes away the soil, a cavity or space can develop under the ground. With the earth above no longer supported, the surface dissolves into the space, causing a sinkhole.

The size and shape of a sinkhole and how quickly it develops depend on the size of the underground void that develops and the amount of material on the bedrock. According to Earth Tech, there are three types of sinkholes--subsidence, solution and collapse--that correspond to the thickness of sediments that sit on top of the limestone.

Differentiating Subsidence, Solution and Collapse Sinkholes

Subsidence sinkholes occur when the overburden--the sediment that sits on the limestone bedrock--is thin and the limestone dissolves slowly. Rainwater penetrating through overlying sediment slowly dissolves the limestone underneath. Over time, small cracks will increase in size, and the rock will erode as the water moves through the layers. The resulting cavities are filled by sediments, causing the land to depress. If water fills the depression, a new lake is formed. Gradually subsiding sinkholes tend to be unaffected by human activity.

Solution sinkholes occur where the overburden is thin or absent, and the limestone is broken down by wind and water from the surface. The process is slow but continuous as the rock erodes.

Collapse sinkholes are the most common type in Florida and form without warning where the overburden is thick. These occur due to erosion as the water from the surface permeates through the rock below it. This erosion causes small to medium cavities in the limestone, and more water flows through to the rock, causing a thinner, weaker void or cavern. When the groundwater levels drop during the dry season, if the roof of the void or cavern is not strong enough to hold the weight of the sediments, the overburden collapses into it, creating the sinkhole.

Sinkhole activity can be dangerous and can occurring suddenly under houses and roads, causing significant damage to property and injury to people. A Florida sinkhole attorney can help you understand what your insurance policy covers if your property has been damaged by a sinkhole.

Article provided by Corless Associates
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