subsidence

1. (geology) A sinking of something to a lower level, especially of part of the surface of the Earth due to underground excavation, seismic activity or underground or ground water depletion, or the rocks in a geological basin, due to continued deposition from above.Examples: "In the early hours of April 28, 1953, it was completely blocked by a subsidence, which caused the death of five persons, when a pair of semi-detached houses collapsed into the cavity."; "Everyone knows that a main line running through a coalfield is prone to speed restrictions because of land subsidence. […] The rate of subsidence may vary from less than an inch a month in the case of a deep seam of coal, to as rapid a decline as 16in a month above a shallow seam. The effect of subsidence on permanent way and civil engineering structures needs no emphasis."; "Subsidence was first noted in the late nineteenth century. An increasing thirst for groundwater, which creates subterranean pockets that are then compressed by the land above, and upriver damming of the Mississippi, which prevents the replenishment of sediments, have undermined the city to the point that it is now thought to be subsiding by up to 12 millimetres per year."countableuncountable