The Science behind Sinkholes
What is a sinkhole? A sinkhole is basically a natural depression in the ground caused by the collapse of the surface layer which results in a void under the ground in where everything around it drains into. They vary in size from 1- 700 meters in both diameter and depth. They can occur suddenly or over a period of time. Types of sink holes? There are two kinds of sinkholes. Cover-subsidence sinkholes these occur over a period of time, a void opens up over time and slowly the soil above subsides, these aren’t as dangerous and can occur over thousands of years. However cover-collapse sinkholes these can be catastrophic. They generally occur in clay, soil leaches into a cave beneath and as it builds up it creates a void the soil then begins to move upwards and suddenly the ground surface will collapse, causing a sink hole.
These occur naturally but humans can also induce them: Drilling is a major contributor as when you remove substances from the ground you lower the natural groundwater table which causes the soil above it to fall. We can also cause them by building cultural features such as parking lots and buildings as you change the hydrologic regime, instead of water naturally soaking into the ground it now exists as run off, concentrating particular areas. Can you predict sink holes? Sometimes there may not be any warning signs. But sometimes there are. Cracks and small depressions in foundations of house and buildings and subtle alterations of regions of houses such as door frames skewing can be indications of a sinkhole forming. Trees can also signal sinkholes when they suddenly start to lean or the soil around the trees are subsiding.
What happens after its finished ‘sinking’? This natural phenomena usually fills itself back up again with soil. This area will then exist as a natural drain becoming a groundwater inlet where rainwater flows into. They can also fill with water and if deep enough will become lakes and ponds.
Footage of one of the largest sink holes to date in Daisetta, Texas