A Least Squares Adjustment of Multi-temporal InSAR Data

Overview & Synopsis

Satellite radar interferometry can be used to spatially monitor small vertical ground deformations. When millimeter accuracy is required, the differential interferometry technique is hampered by the ambiguity with atmospheric artifacts. It is also often difficult to obtain a precise evaluation of the kinematic evolution of ground deformations from a set of time, randomly distributed interferograms. We present the results of a least-squares approach coupled with a temporal filtering and applied to a large data set over the City of Paris. The mean deformation rate and a map of areas affected by time, non-linear deformation events are presented. We show that this approach, which provides a chronologically ordered set of phase screens, allows the retrieval of the kinematic parameters of ground deformations as low as 1 to 2 mm per year. Subsiding areas have been detected, and their evolution in time has been quantified. Such an approach can be useful to fully characterize the kinematic evolution of ground deformations in major cities or desertic areas where large areas have a high degree of coherence and where millimeter accuracy is often required.