A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms

We present a new differential synthetic aperture radar (SAR) interferometry algorithm for monitoring the temporal evolution of surface deformations. The presented technique is based on an appropriate combination of differential interferograms produced by data pairs characterized by a small orbital separation (baseline) in order to limit the spatial decorrelation phenomena. The application of the singular value decomposition method allows us to easily "link" independent SAR acquisition datasets, separated by large baselines, thus increasing the observation temporal sampling rate. The availability of both spatial and temporal information in the processed data is used to identify and filter out atmospheric phase artifacts. We present results obtained on the data acquired from 1992 to 2000 by the European Remote Sensing satellites and relative to the Campi Flegrei caldera and to the city of Naples, Italy, that demonstrate the capability of the proposed approach to follow the dynamics of the detected deformations.

I. Introduction

Differential synthetic aperture radar interferometry (DIFSAR) is a relatively new technique that has been successfully used for generating large-scale surface deformation maps on a dense grid (the displacement field being measured in the radar line of sight) and with a centimeter-to-millimeter accuracy [1]. While the DIFSAR approach has been applied several times to the analysis of a single deformation episode [2]–[6] [7], the interest of the scientific community is now progressively moving toward the study of the temporal evolution of the detected deformations, and some results have already been presented in the literature [8]–[12] [13].