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Sinkholes Gobbling Up Just About Everything

Thursday August 20, 2015    1:02 AM

After a sinkhole swallowed and killed a man as he dozed in his bedroom, another opened in the same suburb, forcing residents to evacuate.

Authorities say a sinkhole opened between two homes in Seffner on Saturday night and the houses have been evacuated as a precaution.

Hillsborough County Fire Rescue spokeswoman Jessica Damico told The Miami Herald the hole was estimated at 3m across and more than 3m deep.

The new hole is about 3km from where Jeff Bush was swallowed up by a hole on the night of February 28 this year.

Bush, 37, was in the bedroom of his home at Seffner, that night when the earth opened and took him and everything else in his room.

The sinkhole - one of hundreds that open up each year in across the United States - was about 4-metres across and ended up destroying Bush's house.

His body has not been found. And is unlikely to be, with engineners saying it was too dangerous to retrieve Bush's body, so they demolished the home and filled the hole with gravel.

Mark Mihal was luckier.

Mihal was on the fairway at the 14th hole of a southwestern Illinois golf course on March 12 when a pit - 5.5 metres deep and 3 metres wide - swallowed him. "I felt the ground start to collapse and it happened so fast that I couldn't do anything," Mr Mihal said. "I reached for the ground as I was going down and it gave way, too. It seemed like I was falling for a long time. The real scary part was I didn't know when I would hit bottom and what I would land on."

Friends managed to hoist Mr Mihal to safety with a rope after about 20 minutes.

One of the most spectacular sinkholes of recent years was in a crowded suburb of Guatemala City when a huge hole - 40m across and more than 30-storeys deep - swallowed an entire building in 2010.

Miraculously, only three people died.

The hole may have taken months or even years to form. But in seconds, it turned into a killer.

Experts suspect a tropical storm, which swept through the country and dumped more than a metre of rain, was likely the final trigger.

While sinkholes are less common in Australia, they do happen.

In 2011, at Inskip beach, north of Tin Can Bay,a 100m-wide section of beach was swallowed by a sinkhole. Campers on Inskip Peninsula watched in awe as chunks of sand were sucked out to sea, followed by trees and signs. Gympie police district duty officer Sergeant Vic Tipman said sinkholes - which can swallow portions of beach as big as houses - were common at Inskip.

"You've got to be careful driving up there," he said.

Given the frequency of sinkholes - especially in some parts of the US - it's surprising more people are not killed.

The scary thing is these subterranean terrors can happen without warning. One minute you're standing on terra firma; the next, the earth beneath your feet has disappeared.

Across Florida this time of year, it's the start of what's unofficially considered the "sinkhole season," State Geologist Jonathan Arthur said.

It coincides with the beginning of the state's rainy season and usually lasts until the end of the northern hemisphere summer.

"Florida is famous for bugs, alligators, pythons, hurricanes and now sinkholes," said Larry McKinnon, a Hillsborough sheriff's office spokesman. "I think our salvation is that for most of the time, our weather is picture-perfect."

But it's also the weather – along with man-made factors – that exacerbate sinkholes, experts said.

Arthur said February is usually when the state is at its driest, but it's also the start of the rainy season. Acidic rain can, over time, eat away the limestone and natural caverns that lie under much of the state, causing sinkholes. Both extremely dry weather and very wet weather can trigger sinkholes, he said.

"An extensive drought can cause soil and sediment over a cavity to be extremely dry and collapse," said Arthur. On the other hand, following Tropical Storm Debby in 2012, dozens of sinkholes formed in counties north of Tampa because of the rain.

In Hillsborough County, an area particularly susceptible to sinkholes where Jeff Bush was killed, engineers and county officials don't know exactly why the sinkhole formed and said they will likely never know.

In Pinellas County, about 50km away from Seffner, fire-rescue workers in the community of Palm Harbor said they asked two people to evacuate a home after the residents reported "extensive cracking on the interior and exterior of the home."

A county building inspector said the home was safe to live in, but the homeowner was seeking an engineer's opinion.

Arthur said he looked at 50 years of data and found that there is usually an uptick of reported sinkholes in February, with an increase until about July, when activity tapers off. December and January have typically low sinkhole activity.

Florida tracks naturally-occurring sinkholes and other ground collapses following a busted water main, development and groundwater pumping for crops.

In 2010, strawberry farmers in eastern Hillsborough County pumped water from the aquifer onto their crops during cold weather so that the water would freeze on the crops, creating a layer of ice that protects the berries. So much water was pumped that more than 65 sinkholes opened in the area and wells went dry.

"When they take water out of the ground it's like taking air out of a balloon," said Bill Fernandez, a Florida sinkhole repair expert.

"When you suck water out of the ground, you change the hydrostatic pressure underground and that's what can cause sinkholes."

Arthur added that moving a lot of dirt around for development can also trigger sinkholes. On Sunday in Largo, a failure in a pipe in a mall's stormwater control system under the parking lot caused the ground to collapse.

"There are a lot of variables," said Arthur. "Sinkholes are naturally occurring. Regardless of human activity they would occur."

Photo: This gigantic sinkhole covered a street intersection in downtown Guatemala City in 2010. A day earlier authorities blamed the heavy rains caused by tropical storm Agatha as the cause of the crater that swallowed a a three-story building. At least three people died. AP Photo/Guatemala's Presidency, Luis Echeverria Source: AP
Photo 2: A truck hangs over the edge of a sinkhole that opened up in the parking lot of Hughes Relocation Service in Salt Springs, Florida, in 2012. Sinkholes are com,mon Florida, espcially during rainy season. AP Photo/The Ocala Star-Banner, Alan Youngblood Source: AP
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