Mobility and topographic effects for large Valles Marineris landslides on Mars

Recent experiments on dry granular flows over horizontal plane bare some similarities with large Martian landslides observed in Valles Marineris (VM). However, Martian normalized runout are twice as large as those that observed in dry granular flow experiments. Numerical simulations on theoretical 2D and real 3D topographies reconstructed from remote sensing data show that slope effects significantly reduce the shift between experimental results and Martian observation. However, topography effects are not strong enough to explain the high mobility of Martian landslides. As a result, other physical and/or geological processes should play a key role into the dynamics of Martian landslides. A new mobility is defined that makes it possible to characterize the dynamics of the flow regardless of the geometry of the released mass and of the underlying topography.