Q&A: What you should know about sinkholes
August 12, 2013|By Eloísa Ruano González, Orlando Sentinel
A 100-foot-wide sinkhole that swallowed buildings at the Summer Bay Resort near Walt Disney World late Sunday was a sudden — and scary — reminder that sinkholes are a Florida reality.
Quick evacuations meant that no one was injured. But like gators and hurricanes, sinkholes are a Sunshine State risk of which both residents and tourists should be aware.
Here are answers to some common questions.
What is a sinkhole?
It’s a depression caused when the earth collapses. Sinkholes can be deep or shallow and narrow or wide. They can cause significant damage and pose a threat to safety when they occur along a highway or near homes and other buildings.
Why do they occur?
They’re caused by the dissolving of underlying limestone. An underground cavity grows larger and what’s below the ground can no longer support the weight above ground, forcing a collapse.
Sinkholes are more likely to occur during rainy seasons that can chip away at limestone underground, according to Todd Hammerle, a state Department of Transportation district maintenance engineer.
Is this area more susceptible to sinkholes?
More sinkholes form in Central Florida than in most other parts of the state, said Clint Kromhout, a geologist with the Florida Geological Survey. The area lacks thick sediments to protect against wearing down of the limestone.
When does a sinkhole stop growing?
It can take minutes to hours for a hole to form. A sinkhole can continue to erode and widen for days — longer if there’s heavy rain.
However, it all depends on the size of the cavity below and the soil above, Kromhout said. Typically, he said, most of the movement occurs within the first 24 hours.
How can I tell if a sinkhole is forming under my house?
People should watch for newly formed cracks on walls or doors that suddenly are difficult to close or open. Cabinets that no longer stay closed also are good signs, Kromhout said. Outdoors, keep your eyes to the ground.
“If you have a yard that’s typically flat and all of a sudden you start to see the sediment sag or go soft in certain areas, it could be a sign of a sinkhole forming,” he said.
Will insurance pay if I have a sinkhole?
Not necessarily. An insurance company doesn’t have to cover sinkhole damage, according to state environmental officials. Insurance companies also have the right to refuse to offer policies to properties deemed high-risk for sinkholes or within an “area” of a sinkholes. DEP officials say the definition of “area” is subjective. Some companies may be more stringent, using private sinkhole data to assign risk to a property, while others may have more liberal policies and offer protection.
Homeowners should shop around and look for companies that are more lenient about what falls under their catastrophic ground collapse coverage, which the state requires they offer to policyholders.
How big can a sinkhole get?
Kromhout said the largest sinkhole on record was in Winter Park in 1981. It measured about 350 feet wide and 130 feet deep in the west side of town.
Mae Rose Owens, who later became Mae Rose Williams, had been playing in her yard with her dog Muffin at the time when she heard “a queer, swishing” noise, the Orlando Sentinel reported. Hours later, a sinkhole swallowed a 40-year-old sycamore tree next to her home on West Comstock Avenue.
Within a day, it had swallowed Williams’ three-bedroom home and yard, five Porsches at a foreign car repair shop, the deep end of an Olympic-size swimming pool and chunks of two streets, causing an estimated $2 million to $4 million in damage. Street vendors later started selling “Sink Hole 1981” T-shirts. The sinkhole was transformed into a lake and named Lake Rose, after Williams.
How many sinkholes are there in Florida each year?
It’s hard to tell. Sinkholes can form in the middle of a farm and may go unreported.
The Florida Geological Survey does keep a database of reported sinkholes statewide. Nearly 3,500 incidents have been entered into the Subsidence Incidence Database since 1954. The figure represents only sinkholes reported since the database was established.
How many people have died because of sinkholes?
Four deaths have been reported in the state, according to Kromhout. He said a death caused by a sinkhole is an “extremely rare situation.”
In March, a Hillsborough County man was swallowed by a 50-foot deep sinkhole. Jeffrey Bush, 37, had been sleeping inside the Seffner home when the earth below his bedroom collapsed.
In most cases, Kromhout said, there have been warning signs, such as the popping, cracking and glass-shattering sounds people at the Lake County resort heard before the sinkhole formed Sunday night.
What is being done to prevent sinkholes?
The state recently received a $1.1 million federal grant for a study to determine which areas are more vulnerable to sinkholes. State officials proposed the study after torrential rainfall from Tropical Storm Debby in 2012 trigged many sinkholes throughout the state, Kromhout said.
He said scientists will study newly formed and existing sinkholes, initially in Hamilton, Columbia and Suwannee counties. The study later will be expanded to the rest of the state, he said. One of the goals is to figure out ways to lessen the impact of sinkholes and loss of life and property.