CNN News:佛羅里達州驚現(xiàn)天坑 專家解讀其中原因

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First up today on CNN Student News, this Florida resident was in his bedroom last Thursday night.

Suddenly the ground underneath opened up and swallowed him.

A sinkhole about 20-feet wide and 50 to 60-feet deep formed underneath Jeff Bush's room.

His brother Jeremy talked about what happened when it started.

"I heard a loud crash like a car came into the house.

And I heard my mother screaming so I ran back there and tried going inside his room.

But when I turned the light on, all I see was a big hole, real big hole."

Jeremy Bush jumped into that hole to try to save his brother, but he couldn't find him.

Officials called off there search on Saturday.

Partly because of the same reason, why workers began demolishing the house.

The sinkhole was expanding and there were concerns the house might collapse at any time.

Sometimes sinkholes are smaller, they might cause the ground to sag or cause a small pound form.

Othertimes they can be huge like this one you are looking at right now from Guatemala.

Or the great blue hole, an underwater sinkhole off the coast of Belize.

Florida actually gets a lot of sinkholes, that's because the ground across a lot of the state is made of limestone, a sedimentary rock.

Nick Valencia explains how that can lead to the sinkholes.

"How do sinkholes form.

Let's break this down for you here.

Sinkholes are usually a naturally occuring event.

Now what happens is, rain water, that heavy rain water sort of sits on top of that bedrock sanding clay.

If you take into account Florida's landscape, it has got a lot of that very porous limestone that allows the rain, the acidic rain to sort of percolate down into the soil forming this cave like sinkholes here.

And also sometimes it's drought that causes this cave-like formations.

And that's further punctuated by that heavy rain that sort of sits on top of there causing this to open up and perhaps, some of the scariest scenarios in Florida, is that you cannot predict sinkholes.

It's highly expensive to predict them yet, you have to use very expensive equipment and it's really tough to pinpoint where the sinkholes are.

In fact, it's so common about the currents in Florida.

All of this little blue dots freckled up and down the state of Florida are past instances of sinkholes.

Now here what happened on Thursday night, an early Friday morning in Hillsboro County at the Bush residents, this is the place that the Florida Department of State says is susceptible to abruptly forming collapse sinkholes.

It's an area that's dominated by them, an area that's had problems with sinkholes in the past. "