A Thesis for the Degree of Candidatus Scientiarum Long-Term Surface Deformation Mapping using Small-Baseline Differential SAR Interferograms

We show that spaceborne Synthetic Aperture Radar (SAR) interferometry is a valuable tool for surface deformation monitoring. By applying the Small Baseline Subset (SBAS) technique to an ERS data set covering Oslo (Norway), we show that the Bjørvika area has been subsiding more than 5 mm/year in the time period of 1992–2000. We review the SBAS algorithm, a new differential SAR interferometry approach for monitoring surface deformation phenomena. The SBAS technique relies on an appropriate combination of differential interferograms created by using SAR image pairs characterized by a small orbital separation (baseline). This reduces the spatial decorrelation phenomena, however, the multi-temporal data set will be divided into several small baseline subsets, separated by large baselines. The singular value decomposition technique is used to “link” the separate small baseline subsets, clearly increasing the temporal sampling rate. Atmospheric and orbital artifacts are filtered out based on the availability of both spatial and temporal information. The topographic phase contribution is removed by using a backward phase simulation, starting from an external digital elevation model. The results are validated by comparison with a similar study and geodetic measurements.