Subsidence
Subsidence is the sinking or collapse of a portion of the land surface. The movement involved in subsidence is essentially vertical; little or no horizontal motion is involved. it may take the form of a sudden, dramatic collapse or a slow, almost imperceptible lowering. In some cases subsidence is a localized phenomenon; in others it is regional in extent.
Subsidence is caused by the existence of caves and results in the formation sinkholes or dolinas.