Land subsidence is a geohazard caused by the sudden or gradual settling (years to decades) of the land surface due to the removal of subsurface material. This can be due to a variety of factors, both natural (such as earthquakes, volcanic activity and compaction of fine-grained unconsolidated sediments) and anthropogenic (for example, mining and groundwater abstraction). It poses a major issue in urban zones where it can cause building collapse and damage to infrastructure that may be a hazard to life and a resource management problem.