Sinkholes are formed when the land surface above collapses or sinks into the cavities or when surface material is carried downward into the voids. A sinkhole or sink hole is defined as a depression formed in the ground because of natural drainage in the surface (Rinkesh, n.d.). It happens when there’s the rock of carbonate, limestone, salt belts, or the rocks which are being cavitated by water inside the rocks lies behind the land. When it rains, water store inside the rocks and, with time being, drains the land surface and creates a sinkhole (Dr. F. Randazzo, 2015).
Sinkholes occur naturally, or sometimes due to man created due to some explosion or bombardment in nearby areas. It has two conditions; we can say human-made only if it is accidentally or with some purpose but caused by a man, but another condition is any natural disaster, earthquake, tsunami, flood, or anything else. It occurs mainly because water from rain stays in the rocks and then rocks start dissolving in the sand and a sinkhole is formed (Brown, 2019).
Sinkholes occurred dramatically like they stay intact for an extended period until underground rocks dissolve and then a sudden collapse of the surface occurs. It creates a big-sized hole in the land surface (Brown, 2019).
The formation of a sinkhole can be naturally or artificially be done. Natural sinkholes are created when rocks under the land start dissolving, like the rocks located near the dead sea, rocks dissolution in Peninsula by limestone presence in the surface (Dr. F. Randazzo, 2015). Human-made sinkholes often formed when buildings, roads, and other construction sites cause water to collect in a specific area, and then this water washes away the rock layer from the ground. Then a sinkhole is formed and it causes a heavy loss.
Sinkholes that are caused by natural factors cause more loss than human-made sinkholes. These are the cavities created on the ground when water erodes the underlying stone layer, or only if the rocks are salt beds, limestone, carbonate rock that can be dissolved naturally by water circulation in rocks (Rinkesh, n.d.). This dissolution of rocks created a sinkhole. Damage could be just a few meters in depth or it could be 100 feet. One sinkhole was formed in the Nongle mountains of China’s limestone in the Gaungxi Zhuang located at the southern part, which measures 656 feet in length, 328 feet broader and 387 feet depth. When you measure it from access, the sinkhole is 1,476 feet deeper from the mountain ridge. Another deepest sinkhole was formed in Chongqing, China which measures 662 meters in depth.
Sinkholes capture the surface drainage due to standing or constantly running water, but dry regions of lands can cause them. Some of the sinkholes are created when there are various caves under the land surface. The roof of the caves collapses and causes a sinkhole to be formed in the cave area. These sinkholes are not that deeper than the sinkholes created by drainage of land under the surface (Brown, 2019).
The artificial processes or human-made sinkhole process includes the explosion in nearby areas and collapsing the mines dug up by man for resources like in Louisiana, Texas, and Mississippi. These are the sinkholes that are away from populated areas, but some of the sinkholes are also formed in the populated areas as there is a drainage system under the roads and buildings. When pipes get old, they corrode and the surface above these pipes starts giving the pipes burden, and eventually, the pipes breaks and causes a sinkhole (Dr. F. Randazzo, 2015). These also occur when extraction and pumping of groundwater, extraction of subsurface fluids, and many more.
One of the biggest and largest man-caused sinkholes was formed in the USA in 1972 in Montevallo, Alabama. It was caused because of the lowering of the level of water in the rock quarry. It was named “December Giant” and somewhere called “Golly Hole” too. It measures 425 feet in length, 350 feet in width, and 150 feet of depth.
Some of the sinkholes are created in chemical industries as the ground is absorbing chemicals for a long term and the surface gets weak and causes a smaller sinkhole in that region. Sometimes, the surface handles the industry’s burden, but a sudden change in a climate like some flood, earthquake, or some other building loss causes the land to create a bigger sinkhole in that area (Rinkesh, n.d.).
Many different reasons cause different types of sinkholes but based on mainly occurred sinkholes; we provide you the main three types of sinkholes.
Cover Collapse Sinkholes:
These are considered the most dangerous type of sinkholes. As from the name, collapse denotes that the surface collapses and suddenly causes a sinkhole. These are the most dramatic sinkholes which generate a significant loss in that region. They mainly occur when the surface below the upper area of land is clay. With the time being, the surface gets drained and the sinkhole formed in a bowl which is a deeper and shallower sinkhole (Dr. F. Randazzo, 2015). These are the dramatic ones, so they always result in devastating land.
These sinkholes usually occur in the limestone regions where the surface layer is thin soil or sand. Dissolution of the rocks of limestone causes intensive sinkhole formation. These sinkholes are also formed where the land’s surface is thin, and water flows behind the surface causes the layer to be thinner and thinner over time. And then finally, the surface collapses and causes a sinkhole which is known as a solution sinkhole (Brown, 2019).
Cover subsidence sinkhole:
The sinkhole formed by a permeable covering of soil and other nonknitted materials is called cover subsidence sinkholes. These sinkholes are not very big as compared to the different types of sinkholes. When the sand or clay on the surface is thicker, it causes the surface to move downward. These types of sinkholes block the water flow behind the surface (Rinkesh, n.d.).
Sinkholes are the most dangerous type of natural or artificial disasters, resulting in the loss of lives, buildings, nature, and many more. There’s no such scale to measure where and when a sinkhole will be formed. But it can be revoked in commercial areas by destroying the rusted and old buildings before they get destroyed and cause a sinkhole (Brown, 2019).
Brown, D. (2019). WHAT ARE THE DIFFERENT TYPES OF SINKHOLES? Retrieved from Foundation Professionals of Florida: https://www.foundationprosfl.com/what-are-the-different-types-of-sinkholes/
Dr. F. Randazzo, A. (2015). ARE THERE DIFFERENT TYPES OF SINKHOLES? Retrieved from Geohazards: https://geohazards.com/are-there-different-types-of-sinkholes/
Rinkesh. (n.d.). What are Sinkholes? Retrieved from Conserve Energy Future: https://www.conserve-energy-future.com/causes-effects-and-types-of-sinkholes.php