INTEGRATED INSAR AND GPS STUDIES OF CRUSTAL DEFORMATION IN THE WESTERN GREAT BASIN, WESTERN UNITED STATES

We compare the level of precision obtainable from GPS and InSAR measurements of the patterns and rates of crustal deformation in the western Great Basin, western United States. In principal InSAR measurements can provide improved geographic resolution of geodetic coverage, complementing GPS networks which are limited by their station spacing. We select the Yucca Mountain, Nevada region as a test case because of its relatively dense coverage with long-running high-quality GPS stations (generally >10 years of data), and its long history of ERS and ENVISAT radar acquisitions (>17 years of data). We apply a time series algorithm to the interferograms in order to estimate linear rates of motion at each pixel, and then adjust the resulting satellite line-of-sight (LOS) rate map to conform to GPS estimates of LOS rate. This aligns the InSAR LOS motion estimates to the GPS reference frame. The resulting LOS deformation map agrees with GPS measurements to within 0.35 mm/yr RMS misfit at the stations and 0.35 mm/yr RMS misfit to the strain map obtained from the GPS velocities. This level of precision is nearly as good as the misfit between GPS velocities and the velocity interpolation (strain map), and represents a considerable improvement over some recent published studies using integrated InSAR and GPS methods. This suggests that the uncertainty in radar LOS rate maps can be brought below 0.35 mm/yr, and that LOS rate maps obtained from InSAR measurements may in future be able to provide a suitable alternative to interpolation of GPS rates which is commonly done in the production of GPS strain maps. The increasing availability of InSAR from satellites such as PALSAR and the future DESDynI will make this approach a valuable tool for hazardous areas.