In various parts of the world the land is literally sinking, giving away to the ongoing changes in water-tables, floods and extreme climate events. India, China and Bangladesh rank high on the list, with close to 600 million people alone in the Indian subcontinent at risk, over the next 10 years.
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 range of economic disasters.