HR: 1340h
AN: G13A-0791    [Abstracts]
TI: InSAR Observations of Time-Dependent Postseismic Deformation in the Mojave Desert: Resolving Tectonic From Non-tectonic Processes
AU: * Schmidt, D
EM: das@uoregon.edu
AF: University of Oregon, Dept of Geological Sciences, 1272 University of Oregon, Eugene, OR 97403-1272 United States
AU: Freed, A
EM: freed@purdue.edu
AF: Purdue University, Dept of Earth and Atmospheric Sciences, 550 Stadium Mall Dr, West Lafayette, IN 47907-2051 United States
AU: B\"{u}rgmann, R
EM: burgmann@seismo.berkeley.edu
AF: University of California, Berkeley, Dept of Earth and Planetary Science, 307 McCone Hall, Berkeley, CA 94720-4767 United States
AB: We examine InSAR observation of the postseismic deformation pattern following the 1992 Landers and 1999 Hector Mine earthquakes to help differentiate the various tectonic and non-tectonic processes. Viscoelastic relaxation of the upper mantle or lower crust, poroelastic response of the crust, and afterslip have all been used to explain various features of the geodetic data following the Landers and Hector Mine events. Our objective is to use the InSAR data to decipher the relative magnitude of these tectonic processes, all of which have distinct spatial and temporal deformation patterns. In this work we emphasize the use of the temporal pattern of deformation to further constrain the postseismic sources of deformation. We processed 250 interferograms along track 127 in the Mojave Desert spanning the time period from August 1992 through the end of 2000. We perform a least squares inversion of the InSAR data to solve for a time series that describes the temporal evolution of the deformation. Unfortunately, several non-tectonic processes complicate the InSAR data. Lateral variations in atmospheric water vapor, which acts to delay the propagation of the radar signal, produce regional artifacts in the line-of-sight displacement. Atmospheric artifacts are reduced by imposing temporal smoothing in the inversion. Additionally, confined aquifers located in the Mojave Desert produce a land subsidence pattern as the water table fluctuates both on a long term and seasonal timescale. Well level data in the basins are analyzed to address the component of land subsidence in the range-change time series. The land subsidence signal can be removed from the time series by assuming that the resulting deformation is elastic. The well level data are linearly scaled and subtracted from the range-change time series leaving the non-linear tectonic signal. The remaining range-change signal is then quantitatively compared to the predicted postseismic deformation for models of the viscous, poroelastic, and afterslip response.
DE: 3210 Modeling
DE: 1829 Groundwater hydrology
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting