New Delhi: According to the US Geological Survey, sinkholes are common where the rock below the surface is limestone, carbonate rock, salt beds, or other kinds of rock which can naturally be dissolved by groundwater circulating through them.
Britain's wettest winter on record has created perfect conditions for sinkholes. Cars, roads and bits of homes have tumbled into the voids created after the ground collapses into subterranean cavities.
Last week a stretch of the M2 in north Kent was closed after a 15ft (4.6m) deep hole was discovered in the central reservation, while on February 2 a teenager's car was swallowed up when a 30ft (9.1m) deep crater appeared in a family's driveway in High Wycombe, Buckinghamshire.
