New radar satellite data reveals the dramatic impact this has had on the stability of the city’s foundations. Between 1984 and 2011, groundwater supplies beneath Tehran sunk by as much as 12 metres, causing an area covering more than 700 sq km (270 sq miles) to subside by several metres. These findings were discovered by combining two decades worth of satellite data which monitored changes in subsidence in both agricultural and urban areas, with data obtained by the newly developed European Space Agency (ESA) Copernicus program, which updates every twelve days. As well as irreversibly damaging the groundwater basins and raising the risk of the city running out of water, the subsidence has resulted in the opening of crevices in the ground and buildings cracking under the pressure of the earth collapsing beneath them.
http://geographical.co.uk/places/cities/item/3052-sinking-tehran