Coseismic crustal deformations of 1994 Northridge, California, earthquake detected by interferometric JERS 1 synthetic aperture radar

Coseismic deformations of the January 17, 1994, Northridge, California earthquake are mapped using interferometric combination of synthetic aperture radar images acquired by the Japanese Earth Resource Satellite (JERS 1) on April 30, 1993, and June 14, 1994. We make an interferogram in a rectangular area with a size of 18.6 km (N-S) by 29.9 km (E-W). Although coherence is not perfect in some areas, fringes in flat and inhabited areas clearly show the coseismic movements. To remove ambiguity of the fringes due to inaccurate orbital information, we use a least squares adjustment to minimize the difference between-the radar and the Global Positioning System (GPS) measurements. The difference between the radar and GPS measurements is less than 3.5 cm. The observed fringe patterns agree with a GPS-based theoretical fault model within 10 cm. We also find a lobed pattern that suggests up to 20 cm of subsidence within a small area. The results suggest that the L band (23.5 cm) radar used by JERS 1 is more robust to spatial and temporal decorrelation than the C band radar used by the ERS 1 and RADARSAT satellites.