Measuring two‐dimensional movements using a single InSAR pair

Abstract

We present a new method to extract along‐track displacements from InSAR data, based on split‐beam InSAR processing, to create forward‐ and backward‐looking interferograms. The phase difference between the two modified interferograms provides the along‐track displacement component. Thus, from each conventional InSAR pair we extract two components of the displacement vector: one along the line of sight, the other in the along‐track direction. We analyze the precision of the new method by comparing our solution to GPS and offset‐derived along‐track displacements in interferograms of the 1999, Hector Mine earthquake. The RMS error between GPS displacements and our results ranges from 5 to 8.8cm. Our method is consistent with along‐track displacements derived by pixel‐offsets, which are limited to 12–15cm precision. The theoretical precision of the new method depends on SNR and coherence. For a signal to noise ratio of 30 the expected precisions are 3, 11cm for coherence of 0.8, 0.4, respectively.