Land Subsidence a Growing Concern

Land subsidence in Iran is way too close to a perilous point to be compared to the global standard set by international land subsidence associations, a senior environment official at the Department of Environment said.
According to Mohammad Darvish, head of Public Participation Office at the Department of Environment, the phenomenon in the country has already reached 140 times the global standard of annually 4mm of land settling.  Land subsidence is defined by scientific references as a gradual settling or sudden sinking of the earth's surface owing to subsurface movement of earth materials. 
Principal causes are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural compaction, gas and oil extraction as well as earthquake. In more humid areas underlain by soluble rocks such as limestone, gypsum or salt, land subsidence is an often overlooked environmental consequence of land- and water-use practices.