Mapping surface displacement using a pair of interferograms: comparative study

Abstract

Interferometric analysis of Synthetic Aperture Radar satellite images (InSAR) measures only one component of ground deformation, in the satellite line-of-sight direction. In order to fully resolve the three dimensional (3D) ground displacement field, InSAR images acquired with different imaging geometries are required. Despite the increase in the number of SAR missions, an area is most frequently imaged by an InSAR pair, one image from an ascending and another from a descending satellite track, with a difference in the incidence angle allowing only partial retrieval of a 3D surface deformation field. In particular, the near-polar orbits of SAR satellites do not allow good retrieval of the north component of displacement. Here we use a model resolution matrix approach for an InSAR pair to quantify the ability to reconstruct the three components of the deformation field. We present and compare the results of the decomposition for three methods, including two widely used techniques and ours that is based on the Singular Value Decomposition (SVD) algorithm. The study case for the comparative analysis is focussed on Bardarbunga volcano area (central Iceland) and complementary tests and modeling are performed using synthetic data. We discuss the retrieved east and vertical components for each decomposition method in terms of approach, viewing geometry, nature, and orientation of the deformation field allowing us to suggest some recommendations when planning the use of a decomposition method.