A massive sinkhole swallowed part of a Florida house that survived Hurricane Irma -- and it's not as rare as you'd think

On Tuesday, a family in Apopka, Florida — about 30 minutes northwest of Orlando — called 9-1-1 when they noticed a corner of their bathroom was descending into the ground.

“I saw big, deep cracks in the bathroom. The tub was sinking and the window was coming loose,” homeowner Ellen Miller told local news station WFTV. “I said, ‘It’s time to go.'”

By the time emergency workers arrived, Miller and her family had moved all the possessions they could to their front lawn. Just minutes later, they watched as the rest of their house was swallowed by a chasm roughly 25 feet long and 15 feet wide.

The family had only recently witnessed the massive destruction of Hurricane Irma.

“We made it through the hurricane. We were really, really lucky, and then this,” Miller told WFTV.

Florida’s sinkhole problem

Winter Park Florida SinkholeThe Winter Park sinkhole in Florida swallowed up sports cars and a community pool in 1981. Its opening was 350 feet wide and 107 feet deep.

It’s not yet known whether the Apopka sinkhole is related to Hurricane Irma, but heavy rains and flooding can sometimes accelerate the phenomenon.

Florida has seen dozens of these types of events over the past several years, due to a combination of geology and natural disasters. According to CNN, insurers in the state processed close to 25,000 claims for sinkhole damage over the course of four years.

In February, a giant hole in the earth swallowed Rachel Wicker’s brother-in-law, Jeffrey Bush. His body was never found.

The family soon learned that their Florida home was sitting on top of a sinkhole. Had Rachel Wicker known about the risk, she and her family would have moved out of the house years earlier, she explained in a 2015 NOVA documentary.

Sinkholes often materialise suddenly and without warning. Frequently, they’re are preceded by a seepage of rainwater into a tiny crack in the ground, which eventually trickles into the sediment beneath. As more rain pools underground, the water begins to carve out a hollow opening deep inside the earth.

Above the widening gap under the ground, sticky, clay-enriched soil keeps the earth together so that, even as the ground beneath starts to open up, the surface remains superficially strong. In these types of situations, it’s tough to notice that anything’s changing.

The void underneath grows larger and larger until the surface finally gives way suddenly, often without any notice.

This is called a cover collapse — and it’s the most dangerous type of sinkhole. These sinkholes typically occur in areas where limestone or other types of water-soluble rock are a primary component of the underground sediment. Florida is underlain in many places by limestone, which is is porous and can suck up large amounts of water. Because liquid passes through limestone easily, the stone is particularly vulnerable to getting worn away by rainwater. As groundwater trickles through, it can create a landscape spotted with caves and sinkholes.

What happened to the Millers fits the typical pattern of sinkhole activity —  a chasm gives way gradually, and loose, clay-free soil above the widening gap falls into the hole over the course of a day or two.

“We watched it all night and it got bigger and deeper and finally, at 4 in the morning, I saw big deep cracks in the bathroom,” Miller said.

However, while sinkholes are common and somewhat terrifying to watch, they rarely lead to fatalities.

“In Florida we are only aware of maybe five fatalities that have ever happened due to sinkhole activity,” geologist Guy Means told The Tampa Tribune

Human-caused sinkholes

Several human activities can turn the threat of a sinkhole into a disaster.

One of them is salt mining. Although most American salt mines were built more than a century ago, we still use them to get the ingredients for everything from table and rock salt to chlorine gas, a key component of plastic.

The problems start when mining companies send drilling pumps into salty seabeds, pillar-like formations that form over millions of years. The drilling pumps dissolve the salt into a brine, creating a watery cavern around the standing pillar.

If the cavern gets too close to an existing sinkhole, soil from the hole leaks into the saltwater cavity, causing the ground above to collapse.

In Bayou Corne, Louisiana, a massive sinkhole opened up when an underground gap in the earth collided with an expanding salt mine, swallowing trees and land. Residents were forced to relocate.

Here are some other massive sinkholes that have opened up across the globe:

Guatemala City Sinkhole 2010

The sinkhole above, which opened up in 2010 in Guatemala City, measures 60 feet across and extends a dizzying 30 stories into the ground. The aerial image of it below gives a better since of its depth.

Guatemala City Sinkhole - Large

The Texas Devil sinkhole, which is now home to millions of bats, has a 40-by-60-foot opening and measures 400 feet deep.

Texas Devil's Sinkhole

Jeffrey Bush’s death appears to be an isolated incident. But the lives of Rachel Wicker and the other Floridians directly impacted by these disasters have been forever changed.

“This is the only home I know. It’s the only home my kids know,” Miller told WFTV.

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