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Located in Green County, east of Bowling Green, Ky., this sinkhole formed about eight years ago; the owners of the farmland where it formed have since pushed old hay rolls into the hole, where a tree has already begun to grow. The walls of the sinkhole are a rich, rusty color, characteristic of the reddish-brown colored silt and dark red clay of central Kentucky's soil.

Credit: Maria Johnson

They've swallowed Corvettes in Kentucky, condos in Florida and homes in Texas. Clearly, sinkholes are not to be sneezed at. But what causes these collapses of supposedly solid ground?

Sinkholes are pits in the ground that form in areas where water gathers without external drainage, according to the U.S. Geological Survey. As water drains below ground, it can dissolve subterranean caverns, particularly in areas where the bedrock is made of water-soluble evaporate rocks such as salt or gypsum or of carbonate rocks such as limestone or dolomite.

Most of the time, sinkholes form gradually. Occasionally, though, the collapse is sudden. Those sudden sinkholes are often the ones that open up and swallow cars, homes and streets. [ In Photos: Stunning Sinkholes]

Geologists divide sinkholes into three types. The first is a dissolution or solution sinkhole. In this type of sinkhole, there is little soil or vegetation over the limestone or other bedrock. Water from rain and runoff slowly trickles through crevices in the bedrock, dissolving it. As a result, a depression gradually forms. Dissolution sinkholes sometimes become ponds if the depression gets lined with debris, trapping water inside. Dissolution sinkholes happen slowly and are generally not dangerous, but one that becomes a pond can drain suddenly if water makes it through the protective bottom layer.

The second type of sinkhole is a cover-subsidence sinkhole. These sinkholes happen in areas where sand covers the bedrock. The sand filters down into openings in the rock, gradually causing the land surface to sink. Continued erosion increases the size of the depression. Like dissolution sinkholes, cover-subsidence sinkholes happen slowly.

The most dangerous type of sinkhole is a cover-collapse sinkhole. In these cases, the bedrock is covered by a layer of clay. Beneath this ground cover, however, water dissolves an underground cavern. Gradually, ground sediments begin to erode, or spall, into the cavern from the bottom. The ground continues to crumble from beneath until only a thin layer remains between the surface and the underground opening. When that layer collapses, the sinkhole opens up suddenly, swallowing any structures on top.

Areas with underlying dissolvable rock are most susceptible to sinkholes. According to the USGS, the most dangerous spots are in Florida, Texas, Tennessee, Pennsylvania, Alabama, Missouri and Kentucky.

There are often warning signs before a sinkhole collapse, however. The ground may slump noticeably, causing fence poles or trees to lean. Subsiding soil might also expose buried surfaces of trees or foundations, according to the Suwannee River Water Management District in Florida.

A structure threatened by a sinkhole may show small cracks, and doors and windows may stick or refuse to shut as the structure subtly settles. Circular patches of wilting vegetation or water gathering in small ponds where it never gathered before can also hint that the ground is failing.

An important warning sign is a "chimney hole" or "chimney sinkhole." These are deep vertical holes of varying sizes with steep sides. Florida officials recommend fencing off chimney holes and reporting them to the county.

The Bimmah Sinkhole is near Dibab village in Oman, an Arab state in the Arabian Peninsula. A winding stone staircase leads down to the sinkhole, which is a beautiful aquamarine and emerald color, with the darker green hues resulting from algae growth in the water.

Credit: Erika Bisbocci ebisbocci flickr

Sinkholes can be very destructive, but they are rarely deadly. An exception occurred in February 2013, when a sinkhole suddenly opened up under a bedroom in a home in Seffner, Fla., sending Jeffrey Bush, 37, tumbling to his death.

Bush's brother Jeremy Bush attempted to rescue him minutes after the sinkhole opened, but found only a dirt-covered hole 20 feet (6 meters) across. Rescue crews deemed the ground too unstable to recover Jeffrey Bush's body, and also condemned the two homes neighboring the residence.

A less tragic sinkhole opened up in February 2014 in Kentucky, swallowing eight cars at the National Corvette Museum in Bowling Green.

An enormous sinkhole in Louisiana in 2012, the Bayou Corne Sinkhole, created an environmental catastrophe by opening up a natural underground oil reservoir. The pit released not only oil, but also methane and hydrogen sulfide to the surface. About 350 people had to evacuate to escape the toxic gases. That sinkhole was caused by an underground mine collapse. [ Dramatic Video: Louisiana Sinkhole Swallows Trees]

An Australian family was shocked in August 2016, when a similar human-influenced sinkhole suddenly opened up in their backyard. The water-filled sinkhole in the town of Ipswich in southeast Queensland was caused by the collapse of an old mine shaft.

Sinkholes can also appear when leaking water or sewer pipes undermine roadways. An investigation by the science news site Phys.org in May 2017 found that urban sinkholes seem to be a growing problem as cash-strapped cities neglect aging infrastructure. In January 2017, for example, a 55,000-pound Hydro-Vac truck sunk into a sinkhole in the parking lot of an auto shop in Oakwood, Georgia. The cause was a crumbling storm drain.

"Blue holes" are water-filled sinkholes in caves or in the ocean. The largest is Pozzo del Merro in Italy, which is at least 1,286 feet (392 m) deep. The Bahamas are home to the deepest Blue Hole with an underwater entrance, Dean's Blue Hole. That sinkhole is 663 feet (202 m) deep.

Blue holes are magnets for tourists, which can cause environmental problems. A 2017 study in the journal Tourism Management found that runoff from the paving of parking lots as well as fuel leakage from visitors' cars contaminated the water-filled sinkholes of Quintana Roo, Mexico, some of which were used by the ancient Mayans as sacrificial pits. Pollution levels rose and fell with the vacation season, the researchers reported.

It's difficult to pinpoint the largest sinkhole in the world - these are unstable and difficult to explore geological features, after all - but a leading candidate is China's "Heavenly Pit," the Xiaozhai Tiankeng. This ancient sinkhole is about 2,170 feet (662 m) deep and 1,760 feet (527 m) wide.

Editor's Note: This reference page was first published on March 15, 2014, and was updated on June 26, 2017, with new information.

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They've swallowed Corvettes in Kentucky, condos in Florida and homes in Texas. Clearly, sinkholes are not to be sneezed at. But what causes these collapses of supposedly solid ground? Sinkholes are pits in the ground that form in areas where water gathers without external drainage, according to the U.S. Geological Survey.

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The ground beneath our feet, our highways, and our cities appears to be very sturdy. But, on rare occasions, that solid ground can simply open up without warning, dropping whatever it was supporting into an unpredictably deep hole. An undiscovered cavern or abandoned mine might collapse, or a broken water main or heavy storm might cause erosion, until the surface becomes a thin shell that drops away all at once. Sinkholes can be anywhere from a few feet wide and deep, to 2,000 feet in diameter and depth. Collected below are images of some of these sinkholes, both man-made and natural, around the world.

View this page Hints: full screen. Skip to the next and previous photo by typing j/k or ←/→.

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The solid ground beneath our feet can, on rare occasions, simply open up without warning, dropping whatever it was supporting into an unpredictably deep hole.

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What are sinkholes?
Sinkholes are pits in the ground that form in areas where water gathers without external drainage. Sinkholes mainly occur as water drains below ground. It can dissolve subterranean caverns, particularly in areas where the bedrock is made of water-soluble evaporate rocks such as salt or gypsum or of carbonate rocks such as limestone or dolomite.

What causes sinkholes?
Sinkholes can be natural or man made. Natural sinkholes occur due to erosion or underground water. They start developing long time before it actually appears. The ground beneath our feet is not as much of a solid structure as we think it is. The ground is made from dirt, along with many rocks and minerals. There is water continually seeping in between the mud, rocks and minerals, as it makes its way down to the ground water reservoirs. As this happens, the water slowly erodes the rocks and minerals. Sometimes the flow of water increases to a point when it washes away the underground structure of the land. And when the structure becomes too weak to support the surface of the earth, it collapses and opens up a hole. This is how sinkholes are formed.

What type of bedrock is more susceptible to sinkholes?
Areas that have a bedrock made of limestone, salt deposits or carbonate rock are most susceptible to erosion and the formation of such holes. These rocks tend to erode as acidic water passes through them. When rainwater passes through decaying plant debris, it tend to become more acidic. Over a period of years, overlying sediments collapse and a sinkhole develops. Sometimes the holes are small, measuring a few feet wide and ten to fifteen feet deep. Others can be hundreds of miles wide and deep. However, all of them can be dangerous for those that get caught in them. There are three major kinds of sinkholes. Their formation is determined by the same geological processes, barring a few differences.

Can humans cause sinkholes?
Yes! Humans are also responsible for the formation of sinkholes. Activities like drilling, mining, construction, broken water or drain pipes, improperly compacted soil after excavation work or even heavy traffic can result in small to large sinkholes. Water from broken pipe can penetrate through mud and rocks and erode the ground underneath and cause sinkholes. Sometimes, heavy weight on soft soil can result in collapse of ground, resulting in a sinkhole. Sinkholes can also form when the land surface is changed.

How quickly do sinkholes form?
Most of the time, sinkholes form gradually. Occasionally, though, the collapse is sudden. Those sudden sinkholes are often the ones that open up and swallow cars, homes and streets.

Why are there so many sinkholes?
Most of the sinkholes we are seeing at the moment are at least indirectly created by human activity. They're occuring just to the sides of human constructions where rain water has been concentrated on a particular patch of ground in the form of run-off from roofs and tarmac. However, these local factors wouldn't matter if it wasn't for the wider picture. The Southeast, where most of the sinkholes have appeared, has not only suffered one of the wettest winters in recent decades, but is also natural sinkhole country as most of the bedrock is the soluble chalk.

What are some notable sinkholes?
In 2010 one of the most devastating sinkholes in recent times hit Guatemala City. An area approximately 65ft wide and 100ft deep collapsed, swallowing a three-story factory and killing 15 people. The sinkhole was caused by a number of factors including an influx of water from Tropical Storm Agatha and leakage from a local sewerage pipe.

On February 12, 2014, a sinkhole some 40ft wide and 20ft deep opened under the floor of the Skydome area of the National Corvette Museum causing a portion of the floor to collapse. Eight rare and one-of-a-kind Corvettes, portions of the display stands and rails, large concrete floor slabs and dirt fell into the sinkhole, causing serious damage to some of the Corvettes. The Corvettes involved have an estimated value of a million dollars.

Do sinkholes happen in other parts of the world?
Yes! The deepest we know about is the Xiaozhai tiankeng in China. Tiankeng is the local term for large sinkholes and translates literally as 'heavenly pit'. This particular example in the Chongqing district is a staggering 662m deep and 626m wide.

Other notable sinkholes include Sima Humboldt in Bolivia, a crater 314m deep and formed from extremely resistant sandstone.

The Great Blue Hole in Belize, a perfectly round hole in the middle of an atoll which is 124m deep.

Finally, Crveno Jezero in Croatia, a 530m deep sinkhole with nearly vertical walls.

How many types of sinkholes are there?
The three major types of sinkholes know to us are : Solution, Cover Collapse and Cover Subsidence.

Solution sinkholes are most commonly seen in areas that have a very thin cover of soil on the surface, exposing the bedrock below to continual erosion by water. As the water percolates through the bedrock, it carries away small parts of the rock with it. As the bedrock erodes, particles collect in the spaces it leaves. Over a period of time, a small depression is formed. It is at this point where the hole forms. The hole is usually bowl shaped and can be quite large. Sometimes the bedrock may collapse all of a sudden to form such a solution sinkhole and other times it happens over time.

The second kind of sinkholes are known as Cover Collapse sinkhole. These take place when the bedrock is covered by a deep layer of soil and earth. Once the bedrock begins to get eroded, crack start forming in the rocky areas around it. When this happens, a number of weak points begin to form in the layers of soil and strata above it. Finally, it comes to a point when the weak points become a large hole within the bedrock that cannot support the weight above it. The cover collapse usually happens in a sudden manner and can create large holes in a matter of minutes.

The last kind of sinkholes are known as Cover Subsidence Sinkhole. In this case, the hole is formed over a period of time. The bedrock here is covered by soil and materials which are not well knitted together. Areas that have soil comprising largely of clay or sand often face the occurrence of this hole. Once the bedrock starts to erode, the clay or sand starts permeating through the cracks and settles into the spaces left behind. Over time, this creates a cavity on the surface of the soil and not under it.

Lesson Plan: Here is a great lesson plan on the science of a sinkhole.

Lesson Plan: This is a fun lesson plan where kids can make a sinkhole in a cup.

Lesson Plan: Here is a great lesson plan on how sinkholes form.

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.

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What are sinkholes? Sinkholes are pits in the ground that form in areas where water gathers without external drainage. Sinkholes mainly occur as water drains below ground. It can dissolve subterranean caverns, particularly in areas where the bedrock is made of water-soluble evaporate rocks such as salt or gypsum or of carbonate rocks such as limestone or dolomite.

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Dr Karl digs deep into sinkhole science

A sinkhole is a void in the ground caused by a collapse of the Earth's surface layer. This usually occurs when the 'stuff' underground - limestone and gypsum - dissolves or shifts as a result of lots of moving water in one area. Heavy localised rainfall or large areas of concreted ground can change the natural water flow.

In May 2010, a giant sinkhole opened up in Guatemala City in Central America. The deep hole (which formed an almost perfect cylinder 20m wide and 30m deep!) swallowed an entire three-storey building! This sinkhole was caused by water shifting the ground's underlying layer of weak volcanic rock.

Last year a small sinkhole formed in the backyard of a family home in Illawong, a suburb of Sydney. A man and his baby were sitting on the couch, when the ground suddenly fell away from beneath them. The collapse was accompanied by a big explosion of dirt, which knocked over a tall tree and a washing line!

About one tenth of the Earth's surface is susceptible to sinkholes, but don't panic - the likelihood of one opening up near you is very small!
In next month's issue, we'll be aiming high and exploring how planes fly!
DID YOU KNOW? The world's deepest sinkhole was in Chongqing, China, reaching down a whopping 662 metres!

DID YOU KNOW? Sinkholes are so common in Florida, USA, that until 2007 it was compulsory for home owners to have Sinkhole Insurance!

DID YOU KNOW? The local geology of Mt. Gambier in South Australia makes it very prone to sinkholes. Luckily, the fairly constant water table and dry conditions have stopped massive numbers of sinkholes from forming.

DID YOU KNOW? The areas of Australia most susceptible to sinkholes include parts of Canberra, Newcastle and Perth, as well as western New South Wales and the Nullabor region.

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sinkholes | science with dr karl | national geographic kids

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Dr Karl digs deep into sinkhole science A sinkhole is a void in the ground caused by a collapse of the Earth's surface layer. This usually occurs when the 'stuff' underground - limestone and gypsum - dissolves or shifts as a result of lots of moving water in one area.

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Informational (nonfiction) 1,033 words, Level Q (Grade 3), Lexile 840L.

Explore one of the strangest natural events on Earth in Sinkhole Science. Seen all over the world, these amazing holes can appear suddenly or develop slowly over years. Readers will learn about the kinds of sinkholes, what causes them, and where they are most likely to occur. Diagrams, maps, and amazing photos support the text.

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Informational (nonfiction) 1,033 words, Level Q (Grade 3), Lexile 840L. Explore one of the strangest natural events on Earth in Sinkhole Science. Seen all over the world, these amazing holes can appear suddenly or develop slowly over years. Readers will learn about the kinds of sinkholes, what causes them, and where they are most likely to occur.

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Sinkholes

Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big. If there is not enough support for the land above the spaces, then a sudden collapse of the land surface can occur. These collapses can be small, or, as this picture shows, or they can be huge and can occur where a house or road is on top.

The most damage from sinkholes tends to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania.

What is a "sinkhole"?

A sinkhole is an area of ground that has no natural external surface drainage--when it rains, the water stays inside the sinkhole and typically drains into the subsurface. Sinkholes can vary from a few feet to hundreds of acres and from less than 1 to more than 100 feet deep. Some are shaped like shallow bowls or saucers whereas others have vertical walls; some hold water and form natural ponds.

Typically, sinkholes form so slowly that little change is noticeable, but they can form suddenly when a collapse occurs. Such a collapse can have a dramatic effect if it occurs in an urban setting.

Areas prone to collapse sinkholes

The map below shows areas of the United States where certain rock types that are susceptible to dissolution in water occur. In these areas the formation of underground cavities can form, and catastrophic sinkholes can happen. These rock types are evaporites (salt, gypsum, and anhydrite) and carbonates (limestone and dolomite). Evaporite rocks underlie about 35 to 40 percent of the United States, though in many areas they are buried at great depths.

Types of sinkholes

Since Florida is prone to sinkholes, it is a good place to use to discuss some different types of sinkholes and the geologic and hydrologic processes that form them. The processes of dissolution, where surface rock that are soluble to weak acids, are dissolved, and suffusion, where cavities form below the land surface, are responsible for virtually all sinkholes in Florida.
DISSOLUTION SINKHOLES
Dissolution of the limestone or dolomite is most intensive where the water first contacts the rock surface. Aggressive dissolution also occurs where is focused in preexisting openings in the rock, such as along joints, fractures, and bedding planes, and in the zone of water-table fluctuation where groundwater is in contact with the atmosphere.

Rainfall and surface water through joints in the limestone. Dissolved carbonate rock is carried away from the surface and a small depression gradually forms. On exposed carbonate surfaces, a depression may focus surface drainage, accelerating the dissolution process. Debris carried into the developing sinkhole may plug the outflow, ponding water and creating . Gently rolling hills and shallow depressions caused by solution sinkholes are common topographic features throughout much of Florida.
COVER-SUBSIDENCE SINKHOLES
Cover-subsidence sinkholes tend to develop gradually where the covering sediments are permeable and contain sand. In areas where cover material is thicker, or sediments contain more clay, cover-subsidence sinkholes are relatively uncommon, are smaller, and may go undetected for long periods.

1. Granular sediments spall into secondary openings in the underlying carbonate rocks.

2. A column of overlying sediments settles into the vacated spaces (a process termed "piping").

3. Dissolution and infilling continue, forming a noticeable depression in the land surface.\

4. The slow downward erosion eventually forms small surface depressions 1 inch to several feet in depth and diameter.

In areas where cover material is thicker, or sediments contain more clay, cover-subsidence sinkholes are relatively uncommon, are smaller, and may go undetected for long periods.
COVER-COLLAPSE SINKHOLES
Cover-collapse sinkholes may develop abruptly (over a period of hours) and cause catastrophic damages. They occur where the covering sediments contain a significant amount of clay. Over time, surface drainage, erosion, and deposition of sinkhole into a shallower bowl-shaped depression. Over time, surface drainage, erosion, and deposition of sediment transform the steep-walled sinkhole into a shallower bowl-shaped depression.

1. Sediments spall into a cavity

2. As spalling continues, the cohesive covering sediments form a structural arch.

3. The cavity migrates upward by progressive roof collapse.

4. The cavity eventually breaches the ground surface, creating sudden and dramatic sinkholes.

Sinkholes can be human-induced

New sinkholes have been correlated to land-use practices, especially from groundwater pumping and from construction and development practices. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created. The substantial weight of the new material can trigger an underground collapse of supporting material, thus causing a sinkhole.

The overburden sediments that cover buried cavities in the aquifer systems are delicately balanced by groundwater fluid pressure. The water below ground is actually helping to keep the surface soil in place. Groundwater pumping for urban water supply and for irrigation can produce new sinkholes in sinkhole-prone areas. If pumping results in a lowering of groundwater levels, then underground structural failure, and thus, sinkholes, can occur.

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Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big.

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Background

Sinkholes are natural depressions in the land caused when limestone and soils dissolve. They form when groundwater removes rock underground. They can form by slow gradual sinking or by sudden collapse of an underlying hole.

Sinkholes are common in about one quarter of the U.S. You can usually identify them as circular or oval low spots in fields that may gather standing water after rains. They can be small or larger than a football field. A sinkhole of any size indicates there was a cavity in the bedrock near the surface. Sinkholes are evidence of a subsurface groundwater, either in the past or present. Formation of a new sinkhole or continued collapse of an existing sinkhole, indicates present day groundwater.

People can affect the location and rate at which sinkholes form. One way sinkholes form is by the removal of large amounts of water from the ground for human use, livestock, or irrigation. This may lower the water table rapidly. Because of the loss of the water, the land surface can collapse into holes already formed in the underlying limestone.

Time Needed

One hour

Materials

8 oz. foam cup

scouring pad or very thin sponge

empty 2-liter soda bottle

sugar

sand

scissors

piece of paper

Procedure

1. Make a hole about the size of your thumb in the bottom of the foam cup.

2. Cut a circle the size of the cup bottom from a thin scouring pad. Place this circle in the bottom of the cup.

3. Place a column of sugar in the center of the cup and surround it by sand. To do this, make a tube by rolling up a piece of paper and place it in the center of the cup. The paper tube should be about the same height and one half the diameter of the cup. Fill the inside of the tube with sugar and the outside of the tube with sand (the sand should be between the paper tube and the sides of the cup). Carefully remove the paper tube. Place a thin layer of sand over the sugar.

4. Cut the bottom off a two-liter soda bottle at about the same height as the foam cup to create a dish. Fill it about one-third full of water. This will symbolize groundwater.

5. Place the cup with the sugar and sand in the water. Watch as the water fills into the cup and the sugar dissolves and runs out. A sinkhole is formed in the cup as the surface sand sinks into the area where the sugar dissolved. (You may need to remove the cup from the dish of water to allow the water to drain out of the cup and the sinkhole to form).

Questions

1. What natural process is demonstrated as the sugar is dissolved by the water and the surface sinks?

2. What type of rock does the sugar represent?

3. What characteristics must a rock have to be suitable for forming sinkholes and caves?

4. What does the water in the dish represent?

5. Why did the sinkhole form only over the sugar deposit?

Further Discussion

Sinkholes are divided into two categories:

1. Bedrock Collapse: This sinkhole forms when the underground rock dissolves enough to totally collapse, bringing surface rock and soil along with it.

2. Surface Arch Collapse: This sinkhole forms when the bedrock has dissolved and voids form beneath the surface rocks and soil. The surface soil continues to erode away into the underground voids. Eventually the soil arch can no longer support itself and collapses into the dissolved bedrock empty spaces.

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Sinkholes are natural depressions in the land caused when limestone and soils dissolve. They form when groundwater removes rock underground. They can form by slow gradual sinking or by sudden collapse of an underlying hole. Sinkholes are common in about one quarter of the U.S.

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Jeff Bush, 36, was killed last Thursday when a sinkhole opened up under his house and engulfed him and his bedroom in Seffner, Florida. Authorities began demolishing the house to get a look at the sinkhole. The house itself was too unstable to enter.

Crews worked carefully to save some of Bush's belongings while also figuring out how to stabilize and fill the hole, which is estimated to be about 30 feet wide and 60 feet deep. The hole is so unstable that nearby houses are also in danger and have been evacuated.

Visit NBCNews.com for breaking news, world news, and news about the economy

How does a sinkhole like this form, especially under a house? How do you know if your house is sitting on top of a potential sinkhole?

We usually see sinkholes on the news when they open up in a roadway and swallow nearby trees or passing cars. Sinkholes, or sinks, mysteriously appear all across the United States, but are mostly found in Florida, Alabama, Kentucky, Missouri, Pennsylvania, Tennessee and Texas. They usually form in areas with soft bedrock or marshy terrains.

Areas where the bedrock is made up of soft minerals and rocks like salt, gypsum, limestone or dolomite are most susceptible. Groundwater running through the rock begins to erode it. Caverns and spaces are created by the eroded rock washing away. The land on top stays intact until the underground space becomes too large, causing the surface to collapse.

Sinkholes usually form where the land does not have good surface drainage. During rains, the water soaks into the ground and stays in the cavern. When the water travels to another location, the land above may not be able to sustain the weight and will collapse.

Humans can also be responsible for sinkholes. Pumping groundwater in construction and development plans may open up weakened areas in the ground. When water is diverted or drainage patterns are changed, sinkholes can also form. If the land is altered, the weight of new material may shift the land and a sinkhole can open up.

For more on sinkholes and facts that could save your life, visit Live Science.

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The Science Behind Sinkholes - Steve Spangler Science

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Jeff Bush, 36, was killed last Thursday when a sinkhole opened up under his house and engulfed him and his bedroom in Seffner, Florida. Authorities began demolishing the house to get a look at the sinkhole. The house itself was too unstable to enter.