Land subsidence in Mexico City mapped by ERS differential SAR interferometry

Land subsidence is a severe problem in Mexico City. The city is built on highly compressible clays and by reason of strong groundwater extraction a total subsidence of more than nine meters has been observed over the last century. ERS differential SAR interferometry was used to map the subsidence of Mexico City between December 1995 and September 1997. For some areas subsidence velocities of more than 30 cm per year with strong spatial gradients of the vertical movements were identified. This remote sensing technique, unique for spatial coverage and resolution, can give significant information for a rational management of the aquifer system, for the planning of new structures and for actions to preserve damaged buildings.