Influence of the scar geometry on landslide dynamics and deposits: Application to Martian landslides

Abstract

Landslides dynamics prediction remains difficult in spite of a considerable number of studies. The runout distance is widely used in analysis of landslide dynamics and in the calibration of the rheological parameters involved in numerical modeling. However, the unknown impact of the significant uncertainty in the shape of the initial released mass on the runout distance and on the overall shape of the deposit raises questions about the relevance of these approaches. The impact of the initial scar geometry on flow and distribution of the deposits is studied here using satellite data and numerical modeling of theoretical landslides, and Martian landslides informed by geomorphological analysis, by varying the initial scar geometry from spoon-shaped to steep wall geometry. Our results show that the runout distance is a very robust parameter that is only slightly affected by the change in the geometry of the initial scar. On the contrary, the lateral extent of the deposit is shown to be controlled by the scar geometry, providing unique insights into the initial landsliding conditions on Mars and makes it possible to accurately recover the volume initially involved, an essential ingredient for volume balance calculation. A feedback analysis of Valles Marineris landslides can be drawn, showing good agreement between numerical results and geomorphological analysis; the geometry of the initial scar inferred from numerical modeling is strongly correlated with the regional tectonic history in Valles Marineris area. © 2011 by the American Geophysical Union.