How does sinkholes affect humans

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. In urban or suburban areas, sinkholes are hazardous because they can destroy highways and buildings. Sinkholes also can cause water quality problems. During a collapse, surface waters may leak into the aquifer, our underground source of drinking water.

Many natural sinkholes cannot be prevented. However, those caused by human activity may be avoided, especially those caused by over-pumping groundwater.

The combination of gravity, loss of buoyancy and water pressure can activate a collapse. By keeping water tables high, water conservation rules and drought restrictions are tools to help prevent sinkholes from occurring. The St.

The increase in population and the spread of the population means that there is a greater chance of encountering a sinkhole. So the odds go up simply by being more proximal. The increase in impermeable surfaces means that rainwater does not infiltrate direction into the ground and percolate into the water table again this may be as a result of urbanisation.

Combine that with an area where the erosion of sand and gravel results in a sinkhole and you have an increased likelihood though by no means a certainty. Building, mining, piling etc in prone areas can alter the loading, drainage and groundwater regime, thus increasing the likelihood of a sinkhole forming, or possibly speeding the process up.

As someone else pointed out, the erosion of rock to form a sinkhole is on a geological timescale albeit a pretty quick one by those standards not really a human one.

However the removal washing out, collapse etc of infilling sediment to expose the sinkhole can be abrupt it's a bit like Kerplunk. It's also worth remembering that some features attributed to sinkholes are a result of historic mining and the collapse of addits. Cornwall for example is littered with old shafts and addits, and historically no-one was very good at keeping track of where they were. Sinkholes can also be caused by a dramatic reduction in ground water, says Cooper.

The physical presence of the water helps to support the cavity. So if you the pump a lot of water out, all of a sudden that material which is water saturated and heavier suddenly collapses in. There have been a number of documented examples in Florida and China and suspected cases in the UK in which abstraction for agriculture has caused the earth to subside.

Ian Stewart the geologist, not the mathematician covered this quite well in Horizon a few weeks back. He put the blame mostly on urban sprawl, but he also said that increased agriculture in some areas was causing increasing volatility in the local water table, which he said could also be a factor.

According to the BGS , Lewis Carroll was inspired by the common sinkholes around Ripon, not far from where he lived as a boy, when he imagined the rabbit hole that lead Alice to Wonderland. Alice fell down- down- down- deep into the earth, following the white rabbit.

Curiouser and curiouser she thought, in this underground wonderland the walls are made of sparkly gypsum - CaSO4. Beneath this area, the gypsum has a water-filled cave system within it, but gypsum dissolves quickly so that the caves enlarge and commonly collapse.

Collapse at Ure Lodge has continued to the present day. It recently caused the destruction of four modern garages and the evacuation of several houses, including the Lodge itself. Subsidence in Ripon, and many other places underlain by gypsum poses a severe constraint on the development of those areas. Well, we are beneath you. Correlation between the tory vote and the likelihood of sinkholes. Art critic Jonathan Jones has written for the Guardian about holes in the earth in art and literature.

Rather than fear them, he says, we should allow them to awe us into delight as they give us an insight into the momentous forces that create the ever-changing world. To build or buy a house, to simply drive to work and expect home to be there when you get back, is actually to take a massive gamble on a turbulent hidden planet. 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? Commonly, surface streams in karst terrane readily lose water through their beds. Contaminated surface waters entering carbonate rocks may carry toxic substances to subsurface streams. Accidental chemical spills and runoff from highways salted in winter to prevent freezing are just two examples of contamination along transportation corridors.

Effluent from commercial and industrial operations along such corridors is also a problem. Caves contain fragile organisms that have evolved in the natural underground environment. Most people think of bats as the most common creature of caves. On the contrary, there is an amazing variety of cave life. Because these animals are highly adapted to stable ecological surroundings, they are particularly sensitive to disturbances, especially the introduction of foreign substances into the groundwater flowing through caves.

Even "clean" fill, such as brush, hay, sawdust, or dirt, may lead to chemical imbalances in the karstic groundwater that adversely affect the ecosystem. This is largely due to the rapid decay of organic matter and consumption of oxygen. Aside from maintaining adequate water resources, it is in the interest of conservation of species endemic to caves that man be concerned with clean groundwater in karst regions.

Occasionally the land surface in karst regions may collapse. Most of these events are triggered by man's activities in the karstic environment. Excessive pumping of groundwater from karstic aquifers may rapidly lower the water table and calls a sudden loss of buoyant forces that stabilize the roofs of cavernous openings.

Man-induced changes in surface water flow and infiltration also may cause collapse. Most sinkholes that form suddenly occur where soil that overlies bedrock collapses into the pre-existing void. Sinkholes are subsidence or collapse features that form at points of local instability. Their presence indicates that additional sinkholes may develop in the future.

Man-made structures in the vicinity of sinkholes are at risk for structural damage unless they have been adequately designed. In populated areas sinkholes are viewed as unwanted holes in the ground. Consequently, there is a great desire to fill them in order to level the ground.

However, naturally developed paths of infiltration are often blocked, leading to potential ponding and flooding on the fill.