DETECTION OF THE SAINT-ETIENNE-DE-TINEE LANDSLIDE USING SAR INTERFEROMETRY AND MODELING

SAR interferometry allows the detection of very smalt ground surface motion (centimetre scale) with high spatial resolution and dense coverage. It can lead to the construction of a continuous displacement field. Using this technique, the landslide of St-Etienne-de-Tinee in the French Alps (44.25 degrees N, 6.96 degrees E) is studied. Surface displacements are determined using an interferogram built with two SAR images taken 9 days apart in August 1991. Synthetic interferograms, calculated for different sliding models, allow us to determine the style of deformation. A translational sliding model with a gradient of displacement from top to bottom, on which three shear zones corresponding to N20 degrees sub-vertical faults are superimposed, account for the observed fringes.