EIGHT YEARS OF MEXICO CITY SUBSIDENCE MEASUREMENTS THROUGH INSAR

The Mexico City Metropolitan Zone (MCMZ), one of the largest agglomerations in the world, has dealt for over 50 years with a subsidence problem mostly caused by heavy groundwater extraction from its aquifer. Monitoring of subsidence in the MCMZ started in 1959 by Mexican water regulating institutions (DGCOH today SACM) through leveling techniques. Synthetic Aperture Radar Interferometry (InSAR) was first applied in the MCMZ on 1999 to obtain mean subsidence patterns. However, the first subsidence time-series developed with InSAR were presented in 2009, for every pixel covering 30 x 30 m, over the 2002-2007 period, using the Small Baseline interferograms (SBAS) approach. Uncertainty on the derived mean subsidence rates was about 1 mm/yr. This work extends the analyzed period to late 2010, thus covering a period of eight years. Deformation analysis to identify linear and non linear components are presented as well as a comparison with leveling measures.