The influence of bedrock topography on the dynamics of two clayey landslides in the Trièves (French Alps)
Résumé
The two large adjacent landslides of Avignonet and Harmalière, affecting thick clayey quater- nary deposits, are located in the Trièves area (French Alps). Remote techniques (Lidar) and GPS measure- ments were used to characterize the two landslides. Results show major differences between the dynamics of the two landslides, both in morphology, displacement rate magnitudes and motion directions. Seismic noise measurements (H/V technique) were performed to map the clay layer thickness. Combined with Lidar derived DEM, these data yielded the paleo-topography of the seismic substratum made of compact alluvial layers and Mesozoic bedrock. The difference in dynamics between the two landslides is likely to result from the pres- ence of a ridge of compact formations at the Avignonet landslide toe, preventing an eastward deep active slid- ing to develop and explaining the observed shallow slip surfaces. To the South, this buttress disappears at the Harmalière toe, favoring a deep sliding in a Southeastern direction with a fast regression of the headscarp, which evolves into a mudslide at its base.
Origine : Fichiers produits par l'(les) auteur(s)
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