Several homes have been evacuated after a sinkhole opened up in the drive of a house in the Black Country town of Wednesbury, on Saturday13 August 2017. The hole is about 3 m wide and 3.65 m deep, and has caused a wall to collapse and partially trapped a car that was parked on a neighbouring drive.
Parked car partially trapped by a sinkhole outside a house in Wednesbury, England. ITV News Central.
Sinkholes are typically caused by the erosion of soft sediments or limestone beneath the surface, creating voids that can open up unexpectedly. On this occasion the hole appears to have been triggered by the collapse of a sewer main, which lead to the washing away sediments beneath the road, and triggering the collapse of a water main, leading to further water loss and further erosion, eventually causing the overlying road to collapse.
The approximate location of the August 2017 Wednesbury sinkhole. Google Maps.
The origin of this particular sinkhole is yet to be determined. It is likely to be related to old coal mineworkings in the area, which was the site of extensive coal mining from the mode nineteenth century onwards, with not all former mines properly recorded, and such mines are prone to collapses, particularly after periods of wet weather. However Wednesbury is also situated on soft limestone, which is eroded over time by acid in rainwater (most rainwater is slightly acidic, though pollution can make this worse), and can collapse suddenly, causing overlying sediments to collapse into the hole and a sinkhole to open up. This can be triggered by human activity, such as pumping water out (which causes the water to flow, facilitating acid dissolution of the limestone), but is essentially a natural process.
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