Landslide scar geometry effect on flow spreading: Application to Martian landslides

Landslides take part in weathering and transport processes on Earth as well as on Mars. Prediction of their dynamics remains difficult in spite of many experimental and numerical studies. Numerous numerical works have been carried out on real landslides cases using DTM (Digital Topographic Model) so as to improve our understanding of their development by comparing results with field observations. Many previous studies have been based on runout analysis in relation to mean dissipation calibration via the friction coefficient. The geometry of the landslide scar may also play a role in landsliding and mass spreading but it is usually unknown. We have tried here to reduce the potential error on mean dissipation resulting from the uncertainty on initial scarp geometry. In addition, from field observations of landslide deposits we have tried to retrieve initial landslide parameters such as initial geometry and volume of material involved. The effect of scar geometry on the spreading flow is studied using a numerical model able to take into account the curvature of the bottom topography.