Florida may not be susceptible to earthquakes, but the geography of the state is the perfect environment for sinkholes. And the sinkholes Florida gets are worsening with each passing year as a result of land development and climate change, according to the Florida Museum’s Thompson Earth Systems Institute.
Sinkholes can be triggered by one of two extremes: drought or too much rain. They typically happen when massive amounts of water dissolve the rock just below the earth’s surface. They’re more common after a big storm, really heavy rainfall or when large amounts of water are displaced by land development activities like drilling or mining.
Sinkholes are really common in some parts of Florida because of a combination of geological factors. Not only does the state see a lot of heavy rain during the Atlantic hurricane season every year, the bedrock under most of the state is typically either limestone or dolostone. Both of these rocks are very soluble and easily dissolve when soaked with enough rain or groundwater.
There’s actually a region of Florida that is so susceptible to sinkholes, some call it “sinkhole alley.”
Where are most sinkholes located?
The most sinkholes in the U.S. mainly occur in seven states. According to the American Geosciences Institute, Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania are the most sinkhole-prone states.
“Many sinkholes occur naturally, but human activities can also cause them,” the institute’s website says. “Over-pumping of groundwater, mining, and leaking pipes beneath roads and buildings are common causes of artificial sinkholes.”
Where is Florida’s sinkhole alley?
Three counties surrounding the Tampa area make up Florida’s “sinkhole alley.”
Pasco, Hernando and Hillsborough counties account for 20,145 of the 27,000 of the reported sinkhole incidences and sinkhole affected parcels on Florida’s sinkhole map – that’s almost 75% of the sinkhole incidents recorded statewide.
Do I need sinkhole insurance in Florida? How much does it cost?
What was the worst sinkhole in Florida?
One of Florida’s biggest sinkhole incidents didn’t occur anywhere near sinkhole alley, though. It happened in the Orlando area in the ‘80s.
In May of 1981, a 350-foot-wide, 75-foot-deep sinkhole opened up in a Winter Park resident’s backyard, swallowing her sycamore tree, three-bedroom home, a nearby car dealership, three Porsches, parts of two streets and an Olympic-sized swimming pool over a the course of a few days. Although that sinkhole was massive, it didn't cause any deaths.
There was another notable sinkhole incident in 2013 that tragically claimed the life of one man, and it did take place in sinkhole alley. Jeff Bush, 37, was laying in his bed in Seffner, Florida, east of Tampa, when the ground opened up beneath him and swallowed his bed with him in it. Bush was presumed dead after first responders couldn't find him in the hole.
The sinkhole was around 20 feet deep and 20 feet wide at its widest points and re-opened again later that year, again in 2015 and once more this summer, a few months after the 10th anniversary of Bush's disappearance.
Is there a sinkhole season in Florida?
Sinkholes can happen any time of year, but according to NBC and Florida public adjusting firm Tailored Law Consultants, the unofficial "sinkhole season" is in the winter.
This is because for the few months each year that Florida gets cold weather, it's also dryer than it is the rest of the year. A really dry period of time sandwiched between months that see a lot more rain is a good time for a sinkhole to form – the bedrock has absorbed a lot of water from the previous hurricane season and is drying out just in time for the rainy season to start again.
Remember, sinkholes form under extremes – extreme rainfall and extreme lack of it. And rainfall in Florida swings like a pendulum throughout the year.
Does insurance cover sinkholes?
Basic homeowners’ insurance typically doesn’t cover damage caused by sinkholes. But all Florida insurance providers are required by state law to offer sinkhole insurance.
You may need to have your insurance provider send someone to your property to determine if you need sinkhole insurance or catastrophic ground cover collapse insurance. Florida’s state-run, not-for-profit property insurance provider, Citizens Property Insurance, offers sinkhole coverage for HO-3 and HO-8 policy holders. But catastrophic ground cover collapse insurance is automatically included in most Citizens’ home insurance policies.
This article originally appeared on Palm Beach Post: Florida's sinkhole alley, other areas where and why the earth opens up