How can humans cause sinkholes

Sinkholes are no surprise - just a sudden revelation of the massive forces that are constantly changing the ground beneath our feet. Catastrophic change and unimaginable metamorphosis are the rule, not the exception, in geology. Sinkholes merely make visible what we choose to ignore. Whereas gypsum can disappear in tens of years. Types of soluble rock in the UK.

Source: BritGeoSurvey pic. Anthony Cooper from the British Geological S urvey BGS says the single most important element in any sinkhole event is water, either in absence or abundance. Too much water can cause soluble rocks such as gypsum and chalk to dissolve and erode, creating underground shafts.

Conversely, if ground water is removed, through abstraction or prolonged drought, underground rocks can crumble under the pressure from above. Sinkholes can occur slowly or dramatically. This is dependent on the material that coats the surface. Sand will subside along with the material beneath. Meaning a gradual sinking. But a more robust material like clay can hold together for much longer, leaving a chasm beneath. Natural sinkholes — as opposed to manmade tunnel or cave collapses — occur when acidic rainwater seeps down through surface soil and sediment, eventually reaching a soluble bedrock such as sandstone, chalk, salt or gypsum, or most commonly a carbonate rock such as limestone beneath.

In a process that can last hundreds, sometimes thousands of years, the water gradually dissolves small parts of the rock, enlarging its natural fissures and joints and creating cavities beneath. As the process continues, the loose, unconsolidated soil and sand above is gradually washed into these cracks and voids. Depending on how thick and strong that top layer is sand will not last long; clay can hold out for millennia , and how close to the surface the void beneath is, the land may be able to sustain its own weight — and that of whatever we build on top of it.

But as the holes grow, there will come a day when the surface layer will simply give way. Sinkhole or pothole? Pothole vs sinkhole? Photo: Sutton Guardian pic. Normally, Britain averages one reported sinkhole each month. But in February five significant holes have opened. A woman is in hospital in Swansea after her car fell into a hole in her garden yesterday. Another in High Wycombe swallowed a Volkswagen Lupo.

But the other important factor is the type of rock below the surface. Soluble rocks like gypsum and chalk, which abound in parts of England and Wales, can erode over time, leaving a chasm beneath our feet. In Britain, scientists differentiate between sinkholes caused by erosion of rocks and the collapse of old mine shafts. Mineral extraction has left the country riddled with unmarked holes, which were not gazetted until the s. This means Britain is prone to both sinkholes and mine collapses.

Sinkholes speak to the same fear as earthquakes and volcanos, they are the moment when our benign home reveals its true and violent nature. We see Earth as an immovable object.

Earthquakes and volcanos are created by forces that transcend humanity, they are beyond our control. But this is not the case with sinkholes. Some are caused by humans. A yawning pit that swallowed a factory in Guatemala City in was caused by a leaking sewage pipe.

Britain has seen a spike in the occurrence of sinkholes in the past month. Geologists say water is the primary factor in any sinkhole event, and Britain has certainly had its fair share of that.

But what other factors are at play? Are sinkholes becoming more common? What role do humans have in their creation?

And can we control them? Please join in the discussion by contributing in the comments below, tweet me or email me. If you are quoting figures or studies, please provide a link to the original source.

Later I will return with my own verdict. Updated at 9. Thanks for the debate today and all the great comments. Watch your step! Ripon This area is well known for its sinkholes, caused by a large deposit of highly erodible gypsum. Human activity has little to do directly with the formation of sinkholes.

Though most are only 10 to 12 feet in diameter, sinkholes have been known to expand to hundreds of feet in diameter. Rainfall percolating, or seeping, through the soil absorbs carbon dioxide and reacts with decaying vegetation, creating a slightly acidic water. That water moves through spaces and cracks underground, slowly dissolving limestone and creating a network of cavities and voids. As the limestone dissolves, pores and cracks are enlarged and carry even more acidic water.

Sinkholes are formed when the land surface above collapses or sinks into the cavities or when surface material is carried downward into the voids.

Drought, along with resulting high groundwater withdrawals, can make conditions favorable for sinkholes to form. Also, heavy rains after droughts often cause enough pressure on the ground to create sinkholes. Year Select Year Apply Filter. Date published: October 16, Date published: June 8, Date published: March 2, Attribution: Water Resources.

Date published: November 8, Date published: June 18, Date published: June 11, Below are publications associated with groundwater, sinkholes and land subsidence. Year Published: A primer on ground water Most of us don't have to look for water.

Baldwin, Helene L. View Citation. Filter Total Items: 4. Galloway, Devin L. Year Published: Measuring land subsidence from space No abstract available. Year Published: Land subsidence in the United States This report explores the role of science in defining and understanding subsidence problems, and shows that the optimal use of our land and water resources may depend on improved scientific understanding to minimize subsidence.

Year Published: Ground water and the rural homeowner As the salesmen sang in the musical The Music Man, "You gotta know the territory. Waller, Roger M. Below are news stories associated with sinkholes and land subsidence. Filter Total Items: 2. Date published: October 1, Attribution: California Water Science Center. Date published: November 18, Below are FAQ associated with sinkholes and land subsidence.

What is the difference between a sinkhole and land subsidence? Sinkholes are just one of many forms of ground collapse, or subsidence. The principal causes of land subsidence are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural How many sinkholes open up in a year? There is no database of sinkhole collapses for the United States, so these data are unavailable.

Some individual state geologic surveys track reported collapses within their state. Many sinkhole collapses are not reported to authorities or news organizations, and many occur in rural areas where they are unobserved. What is a sinkhole? Save For Later Print. Pictured is a large sinkhole containing an electrical utility line that opened up along a gravel road in Centre County, PA, after a series of heavy rain storms.

Photo: Bryan Swistock, Penn State. Did a cavity just open in your yard, as if you were in Jules Verne's Journey to the Center of the Earth? How could this happen? A sinkhole is one of several things that can lead to land subsidence, where the ground sinks gradually or suddenly. Sinkholes can look the same on the surface regardless of the cause. This article addresses some of those collapses caused by human activity.

The material supporting the surface moves downward and leaves the surface to collapse. This occurs often occurs naturally when the underlying carbonate bedrock such as limestone or marble dissolves. That's how caves come to into being. But sinkholes can also be a result of mining, washing away from leaking utility lines, or decay of buried material. Such cavities are an unfortunate but common problem that may occur five to ten years after construction.

Like natural sinkholes, these underground cavities form gradually, but can appear in your lawn overnight. Such cavities typically develop where a construction crew buried organic debris such as tree branches, brush, stumps, and construction materials.