A Sainsburys Local store in Ripon, North Yorkshire was evacuated yesterday after a sinkhole opened up in an alleyway behind the store.
The North Yorkshire Fore Service confirmed that it was called to the scene yesterday morning but no action was taken.
The British Geological Survey has said that the ground collapse is likely to be caused by dissolution of gypsum in the Permian rocks that underlie the city.
The BGS added: “The natural rate of occurrence of these features appears to be in the order of one every three to five years. However, the ability of water to dissolve gypsum depends on how much gypsum is already dissolved in the water such that fast flow paths of fresh water will dissolve gypsum more readily than slowly moving groundwater that is partially saturated with gypsum. As a consequence, the ground conditions in Ripon are particularly vulnerable to increased volumes of infiltrating water.”
According to the BGS, an increased rate of sinkhole formation may be a natural occurrence due to intense rainfall, particularly in conjunction with desiccation and cracking of the ground facilitating water ingress or a consequence of any damage to water bearing services.
“Extremes of weather can result in ground movement and shrinkage, therefore this may have a direct or indirect consequence in terms of the rate of sinkhole formation.”