HR: 15:10h
AN: G43A-06    [Abstracts]
TI: The temporal and spatial distribution of deformation in the western Salton trough from 1992-2001 as observed by InSAR
AU: * Mellors, R J
EM: rmellors@geology.sdsu.edu
AF: Department of Geological Sciences, 5500 Campanile Dr. San Diego State University, San Diego, CA 92122 United States
AU: van Zandt, A
EM: affyvz@yahoo.com
AF: Department of Geological Sciences, 5500 Campanile Dr. San Diego State University, San Diego, CA 92122 United States
AU: Rojas, O
EM: rojas@sciences.sdsu.edu
AF: Department of Geological Sciences, 5500 Campanile Dr. San Diego State University, San Diego, CA 92122 United States
AB: We use InSAR data to examine the temporal and spatial distribution of deformation in the Western Salton trough in Southern California. A set of 87 ERS-1 and ERS-2 interferograms (track 356, frame 2943, descending) covering the region and spanning a time period from 1992 to 2000 have been compiled. The interferograms show a combination of both tectonic (mainly along the Superstition Hills and Elmore Ranch faults) and groundwater related (centered in farming areas) deformation signals. We invert the dataset to resolve the evolution of slip over time using a least-squares approach constrained with GPS data. Error terms for the DEM, orbital, and atmospheric effects are addressed using a combination of spatial and temporal filtering. The results show that the tectonic slip decreases with time, as expected for long-term post-seismic slip following the 1987 Superstition Hill/Elmore Ranch earthquakes. The tectonic slip also appears to be episodic in nature. In contrast, the groundwater-related subsidence shows a more linear trend with time. 2D modeling of the observed tectonic slip (assuming purely horizontal movement along a vertical strike-slip fault) indicates that slip along the Superstition Hills fault extends from the surface to an average depth of 4 km. The average horizontal slip from 1992 to 2001 varies from 5 to 10 mm per year along the fault. Slip along the Elmore Ranch fault is slower and appears to be distributed over a wider zone, possibly suggesting that creep does not extend to the surface.
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
SC: Geodesy [G]
MN: Fall Meeting 2005