DISCRIMINATION OF GEOPHYSICAL PHENOMENA IN SATELLITE RADAR INTERFEROGRAMS

Various geophysical phenomena are recorded in the interference patterns formed by differencing two synthetic aperture radar (SAR) images. The fringes generated by the topographic relief can be removed using a digital elevation model (DEM). The remaining fringes map the change in satellite-to-ground range which occurred between the acquisition times of the two images. By comparing different pairs of images spanning different intervals of time, it is possible to discriminate between geophysical signal and interferometric artifact. Here we apply this pair-wise logic to the area around the 1992 Landers, California earthquake using SAR images acquired by the ERS-1 satellite. The range varies with time as a constant, step, impulsive, or sloping function. Examples of each type include a DEM error, an aftershock, two atmospheric perturbations, and postseismic afterslip, respectively. Their signatures are identified and separated using the pair-wise logic.