What are Sinkholes?
Cenotes Are a Type of Sinkhole
How Are Sinkholes Created?
Sinkholes are frequently in the news, such as in the tragic death of a Florida man whose bedroom floor opened up and sucked him into the earth in late February of 2013.
Despite the elements of mystery and surrealism surrounding events such as the deadly sinkhole collapse in Florida, these frightening gaps in the earth's natural infrastructure are fairly common geological formations throughout various parts of the world.
Sinkholes are naturally formed 'holes' in the earth\h caused by the erosion of the rock surrounding the holes or depressions.
The erosion (also known as the karst process) happens when water is introduced into rock that is permeable and 'eats' at it, almost chemically, thereby weakening its structure.
These formations are known by several names across the globe, such as swallow holes, sinks, cenotes, swallets, shake holes or dolines.
Florida, where the horrifying event mentioned above occurred, is known for having many 'sinkholes,' which may not have been an issue hundreds of years ago (or even several decades ago), but with a huge population living on the host soil and rock, collapses such as the one that killed Jeff Bush, the man swallowed up in late February, are an increasing hazard for those who might live or work near an area near sinkhole formations.
Swimming in a Cenote Sinkhole: Not all Sinkholes are Bad
What Happens When Sinkholes Cave in?
Underwater Cave Formed by a Sinkhole
How do Sinkholes Collapse?
Although sinkholes are found in many parts of the United States, Florida is known for having more of these formations than any other state in the Union.
Sinkholes are so common throughout the Sunshine State that there are special and separate insurance clauses to cover their collapse for homeowners and others who have property there. And some homes or businesses may not be insurable, due to the extreme risk in that area.
A collapse can happen when the rock surrounding the hole becomes fragile or brittle enough to cave in.
If you live near (or over) a sinkhole, there are sometimes signs of a collapse that can warn you to evacuate the area or move valuable equipment away from it (if the sink is in an open area) to avoid injury or loss.
A qualified inspector is the best source to turn to if you see signs (such as cracks in the foundation, or holes appearing in the earth) that might indicate a collapse.
Even if the signs are in your home, where you might normally feel safe, do not delay in getting an assessment, if needed, and leave the property immediately if there are signs of active collapse.
What Places Have Sinkholes?
The answer is easy - all over the world.
Okay, that's a bit too broad.
Some areas are known for having large numbers of these 'holes,' such as Papua New Guinea and Florida.
Other areas may not have the thousands of holes found in the places mentioned above, but have gigantic examples of sink formations, such as the Xiaozhai tiankeng found in Chongqing, China, which is more than 2,000 feet deep and is the largest known example in the world.
The Yucatan Peninsula, as well as other areas in Mexico, such as Queretaro, have numerous sinkhole formations (generally known as cenotes in that country).
The sinks, or cenotes, in Yucatan are thought to be formed from the impact of an enormous meteor that slammed into the earth just off of what is now the tip of that peninsula. Those sinks are now popular and scenic tourist spots and swimming holes, attracting thousands of people each year, who enjoy paddling about in the waters and relaxing under the vine-covered trees that often line the banks.
But when sinkholes swallow up homes, businesses and people, they are not so inviting and innocent.
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How to Avoid a Sinkhole
If you're buying property, and if you're worried or fearful that there could be holes underneath your home, check with local building authorities to see if there are risks where you live.
Although sinkholes have been known to open up under businesses and homes, these incidents are somewhat like shark attacks - they're not hugely common, but they're widely covered in the news.
Most populous areas have already been researched for instances of sinkholes. Various factors can affect whether an area is at risk of collapse, such as the depth of topsoil (Florida has several feet of soil, which means more water can collect and be held in the soil above the rock than in areas with shallow topsoil). The type of rock underneath soil is another factor - some rock is more permeable than others.
Check with stake or local land authorities to find out the geological structure and elements of the area in which you plan to live. They will have the best information available, as well as tips on what to do if you live in an area with some risks.