'American Association for the Advancement of Science (AAAS)'
Abstract
Interferometric Synthetic Aperture Radar observations of surface deformation
due to the 1999 Hector Mine earthquake reveal motion on several nearby faults
of the eastern California shear zone.We document both vertical and horizontal
displacements of several millimeters to several centimeters across kilometerwide
zones centered on pre-existing faults.Portions of some faults experienced
retrograde (that is, opposite to their long-term geologic slip) motion during or
shortly after the earthquake.The observed deformation likely represents elastic
response of compliant fault zones to the permanent co-seismic stress changes.
The induced fault displacements imply decreases in the effective shear modulus
within the kilometer-wide fault zones, indicating that the latter are mechanically
distinct from the ambient crustal rocks
