Measuring ground displacements from SAR amplitude images: Application to the Landers Earthquake

TLDR

The accuracy of displacement measurements depends on the characteristics of the SAR images. ERS SAR amplitude images are used with a sub‑pixel correlation method to produce a two‑dimensional displacement field with independent measurements every ~128 m in azimuth and 250 m in range. For the Landers earthquake, the method achieves 0.8 m 1‑σ uncertainty in range and 0.4 m in azimuth, mapping major fault ruptures with sub‑kilometre accuracy and comparable coseismic deformation to 92 GPS stations, and while less precise than interferometry, it is more robust and provides complementary range‑insensitive information.

Abstract

ERS SAR amplitude images are utilized to map ground displacements from a sub‐pixel correlation method. It yields a ground two‐dimensional displacement field with independent measurements about every 128m in azimuth and 250m in range. The accuracy depends on the characteristics of the images. For the Landers test case, the 1‐σ uncertainty is 0.8m in range and 0.4m in azimuth. We show that this measurement provides a map of major surface fault ruptures accurate to better than 1km and information on coseismic deformation comparable to the 92 GPS measurements available. Although less accurate, this technique is more robust than SAR interferometry and provides complementary information since interferograms are only sensitive to the displacement in range.