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Published August 30, 1996 | public
Journal Article

Postseismic Rebound in Fault Step-Overs Caused by Pore Fluid Flow


Near-field strain induced by large crustal earthquakes results in changes in pore fluid pressure that dissipate with time and produce surface deformation. Synthetic aperture radar (SAR) interferometry revealed several centimeters of postseismic uplift in pull-apart structures and subsidence in a compressive jog along the Landers, California, 1992 earthquake surface rupture, with a relaxation time of 270 ± 45 days. Such a postseismic rebound may be explained by the transition of the Poisson's ratio of the deformed volumes of rock from undrained to drained conditions as pore fluid flow allows pore pressure to return to hydrostatic equilibrium.

Additional Information

© 1996 American Association for the Advancement of Science. 4 June 1996; accepted 17 July 1996. We thank E. Ivins and P. Segall for discussions on postseismic deformation processes, A. Sylvester for sharing unpublished results of leveling across the Homestead Valley fault, and two anonymous reviewers for constructive suggestions. The ERS-1 radar data were provided by the European Space Agency. The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA, and at the U.S. Geological Survey.

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