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Interferometric synthetic aperture radar (InSAR) has great potential to detect and quantify land subsidence caused by aquifer system compaction. InSAR maps with high spatial detail and resolution of range displacement (+/-10 mm in change of land surface elevation) were developed for a groundwater basin (similar to 10(3) km(2)) in Antelope Valley, California, using radar data collected from the ERS-1. satellite. These data allow comprehensive comparison between recent (1993-1995) subsidence patterns and those detected historically (1926-1992) by more traditional methods. The changed subsidence patterns are generally compatible with recent shifts in land and water use. The InSAR-detected patterns are generally consistent with predictions based on a coupled model of groundwater flow and aquifer system compaction. The minor inconsistencies may reflect our imperfect knowledge of the distribution and properties of compressible sediments. When used in conjunction with coincident measurements of groundwater levels and other geologic information, InSAR data may be useful for constraining parameter estimates in simulations of aquifer system compaction.