Induced Sinkholes: An Engineering Problem

Induced sinkholes are those related to man's activities, whereas natural sinkholes are not. Induced sinkholes are divided into two types: those resulting from a decline in the water table due to ground-water withdrawals and those resulting from construction. Almost all induced sinkholes occur where cavities develop in residual or other unconsolidated deposits overlying openings in carbonate rocks. The downward migration of the deposits into underlying openings in bedrock and the formation and collapse of resulting cavities are caused or accelerated by a decline in the water table that results in: (1) Loss of buoyant support; (2) increase in the velocity of movement of water; (3) water-level fluctuations at the base of unconsolidated deposits; and (4) induced recharge. Most sinkholes resulting from construction are due to the diversion of drainage over openings in bedrock.