ON THE DERIVATION OF COSEISMIC DISPLACEMENT-FIELDS USING DIFFERENTIALRADAR INTERFEROMETRY - THE LANDERS EARTHQUAKE

We present a map of the coseismic displacement field resulting from th e Landers, California, June 28, 1992, earthquake derived using data ac quired from an orbiting high-resolution radar system. We achieve resul ts more accurate than previous space studies and similar in accuracy t o those obtained by conventional field survey techniques. Data from th e ERS 1 synthetic aperture radar instrument acquired in April, July, a nd August 1992 are used to generate a high-resolution, wide area map o f the displacements. The data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30-m re solution element in a 113 km by 90 km image. Our coseismic displacemen t contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake. Fine structure observe d as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing. Comparison of th ese data with Global Positioning System and electronic distance measur ement survey data yield a correlation of 0.96; thus the radar measurem ents are a means to extend the point measurements acquired by traditio nal techniques to an area map format. The technique we use is (1) more automatic, (2) more precise, and (3) better validated than previous s imilar applications of differential radar interferometry. Since we req uire only remotely sensed satellite data with no additional requiremen ts for ancillary information, the technique is well suited for global seismic monitoring and analysis.