Mexico City subsidence analysis assisted by InSAR

Mexico City is one of the most populated cities of the world. Its aquifer is thus overexploited causing subsidence rates reaching up to 40 cm/year mainly due to the soil compaction. Previous to this work, we mapped the spatio-temporal patterns of the Mexico City subsidence by differential radar interferometry, using 38 ENVISAT images acquired between end of 2002 and beginning of 2007. From the inversion of 71 small baseline unwrapped interferograms we obtained increments of radar propagation delays between the 38 acquisition dates using an algorithm for time series analysis that was best suited to our database. Accurate deformation time series were then derived over the metropolitan area of the city with a spatial resolution of 30 x 30 m. In this work we present some analysis of the nonlinear components present in the time series obtained.