Land subsidence in metropolitan areas is a major human-induced geological hazard that affects buildings and urban infrastructure and results in severe economical consequences for both individuals and local government administrations. It is caused by sediment consolidation in response to both natural and anthropogenic processes. In many urban areas (e.g., Mexico City, New Orleans, Venice), subsidence occurs due to massive water extraction, which increases with increased population. In order to minimize the subsidence risk, it is important to monitor the subsidence and its development over time. In this study we use InSAR observations that provide wide-scale measurements with cm/yr-level precision, to calculate surface deformation in major South America metropolitan areas. We obtain ALOS data that were acquired over major South American metropolitans between 2007-2011 and are distributed by the Alaskan Satellite Facility (ASF). We processed the data using the PySAR algorithm (Fattahi, H. and Amelung, F., 2013), which is based on the SBAS technique. Preliminary results of ALOS data acquired over Bogota (Colombia), Lima (Peru), Buenos Aires (Argentine), Sao Paulo (Brazil) yielded detectable subsidence in Bogota and Sao Paulo, but not in Lima and Buenos Aires. These preliminary results suggest that inland metropolitans are more susceptible to land subsidence than coastal metropolitans, most likely due pumping-induced saltwater intrusions to near-shore aquifers. We plan to continue analyzing ALOS data from 15-20 most populated South American metropolitans in order to evaluate the magnitude and time evolution of land subsidence in these highly populated areas. References. Fattahi, H. and Amelung, F., (2013), DEM Error Correction in InSAR Time Series, IEEE Transactions on Geoscience and Remote Sensing, vol. 51 no.7, doi: 10.1109/TGRS.2012.2227761.