What is a sinkhole and how is it formed?

The residents of Surrey village of Godstone have been evacuated this week after the opening of two sinkhols with large parts of high street.

The original hole first appeared late Monday night, Till Tuesday afternoon meal has been growing at least 65 feet (20 meters) long.

Sinkhole is not uncommon in the UK, but can sometimes appear suddenly. What can be the reasons and should we be more concerned about them?

A synchronous surface has a depression because the underlying rock collapsed.

They can be sauce -shaped or may look deeper like a shaft. If they are in manufactured areas, they may appear more irregular as a road or distort another structure size above.

In Godstone, the collapsed land is under a road that partially hiding the size of depression.

Sinkhole can appear for many different reasons – it is often caused by geology but human factor can also be a reason.

One of the most common causes for synchhole is when rocks like limestone or chalk break. This is because the carbon dioxide dissolves in rain water from the air to make carbonic acid – it then rotates through the rock and reacts with it, causing it to dissolve.

Sometimes this process can gradually be gradually, where depression grows over time.

In other examples, the limestone sits under another layer of rock, which means that as soon as it is dissolved, there are no immediate signs on the surface.

The overlapping rock, sometimes soil or sandstone, will suddenly fall into depression – called ‘Fall Sinkhol’.

These are the most common in South Wales where sandstone rocks are lying on the caves in limestone.

But human activities can also accelerate the formation of sinkhole or cause the ground to collapse in a similar way.

The British Geological Survey for South-East England regional geologists Andrew Farent, what happened in Godstone and it is not a true synchronist.

He said that one theory is that the head of a burst water has caused sudden water influx in the sandstone beds, the way the rock is out.

The Weldon Cave and the Pete Burges of the Weldon Cave and Mines Society stated that a mine marked as “sand pits” can be seen directly under the synchhol on the 19th -century maps.

He said that sand was dug from the pit and used for the purposes of construction and horticulture.

Mr. Farrant said that the sand was filled in the pit, but he said that there was a significant historical mining in the area and cannot be dismissed that there were some precious pits and mines that were manufactured.

They are common in Britain due to the abundance of limestone and chalk rock and historical mining activities.

Limestone and chalk shallow are formed by the deposits and compression of micro -organisms found in hot seas. Millions of years ago the UK was located in the south towards the equator and was very hot with parts of the country – to create ideal conditions for these rock types.

Risk in Vanessa banks, shallow Giohazards expert and British Geological Survey, told the BBC Radio 4 PM program: “Sinkhol is in Sinkhol Sites, but many are not recorded as they are in remote areas.”

He said that meteorological conditions play a role as the extreme decline can flush the water through the rocks or pressurize the main infrastructure of the water.

Last December, there were about 30 houses Marthyr withdrawn in Tydfil After the collapse of the ground, and in 2014, the synchhols occurred from the normal rate in South-East England after the rapid storm position.

The ‘collapse synchron’ that can be seen like cracks or sub -parts, suddenly and without any warnings on the surface.

In 2010, a sinkhole that measures 20 meters and 90 meters deep appeared in Guatemala City, resulting in a person who died. In this case, heavy rains and poor drainage are weakened by the underlying rock.

And in January, a truck driver was to be rescued in the Japanese city of Yashio after the land collapsed due to a burst pipe.

In case of disintegration, sinkhols can indicate geologists that if the underlying rock is made of chalk or limestone, which areas are at high risk. The local planning authority reviews geology and any possible risk for any new development in the UK.

But the reader in Geology and Geotechnical Engineering at Brunel University, Dr. Coalins said that in this case where the infrastructure of water plays a role, it is difficult to predict the collapse of potential ground.

“The breakdown of the pipe highlights the challenge that comes with the burial infrastructure because they are often buried at a depth of more than one meter. The depth is to reduce the effect of deep freeze during the very cold winter.

“Unfortunately, this makes them difficult to monitor and can be difficult to repair, including the replacement of soil in the excavated hole after completion of repair,” he said.