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

Six different interferograms of the ''La Clapiere'' landslide were der ived from ERS-1 SAR images during the period Aug. 20-Sept. 4, 1991. Th e coherence of the associated images is shown to remain significant ov er most of the surface of the landslide during the two weeks of the su rvey. The interferograms are remarkably similar, and indicate steady-s tate displacements over at least 12 days. The displacement field deriv ed from the interferograms is shown to be characterized by a non-unifo rm displacement gradient from top-to-bottom and reveals a significantl y faster motion of the western parr of the landslide. The amplitude of the motion deduced from interferometry is shown to be in good agreeme nt with ground measurements. Finally, SAR interferometry is shown to b e able to evidence small-scale instabilities which may not be observed with discrete ground measurements.