OBSERVATIONS OF CO-SEISMIC AND POST-SEISMIC SLIP FROM THE HECTOR MINE EARTHQUAKE AS RECORDED BY INSAR

Surface deformation produced by the 1999 Mw 7.1 Hector Mine earthquake was well-recorded by interferometric synthetic aperture radar (INSAR). In addition to the substantial deformation due to the main rupture, a variety of secondary effects, both co-seismic and post-seismic, were recorded. These effects include apparent co-seismic triggered slip and three distinct types of post-seismic slip. The triggered slip occurs along at least 20 km of the Calico fault. Amplitude of the slip may be related to the surface geology. The post-seismic deformation includes broad subsidence and uplift along the main fault, localized subsidence in a narrow trough along the fault zone itself, and patches of deformation isolated from the main fault. Most of the deformation occurred in the first 40 days after the main shock, although each type of post-seismic deformation appears to be caused by a different mechanism. The broad subsidence and uplift may be related to deeper post-seismic slip. The isolated patches of deformation are likely due to aftershocks. The cause of the fault zone subsidence is uncertain. We compare these observations with the surface geology and with INSAR observations of the 1992 Landers, California earthquake.