A 2.5Mm³ of rocky mass has been released on the 18^th of September 2004. The observed runout is about 2km. On the avalanche path, the presence of a glacier make this example interesting for dynamics analysis. Furthermore, some seismic records of this event have been performed.
Numerical simulation of the rock avalanche respectively without glacier and with glacier taken into consideration. Landslides can generate seismic waves. By comparing recorded and simulated signals generated by landslides new insigths dynamics can be performed on granular flows. In addition, this is a powerful tool for model validation.
Seismic record of Thurwieser rock avalanche at Fuorn Station (Data provided by University of Milano , Italia, G. Crosta).
Comparison between records (in red) and modelisation (green and blues). The presence of a glacier on the avalanche path has huge impact on dynamics and thuson generated seismic waves. Modelisation without glacier (green) does not fit all mouvment of the ground whereas modelisation with glacier taken into consideration (blue curve) has a good match with recorded data.
This study shows how seismic signal can give informations on dynamics of landslide and how it could be a good tool for numerical model validation.


Some references:

P. Favreau; A. Mangeney; A. Lucas, N. M. Shapiro; , G. B. Crosta; F. Bouchut, LANDSLIDE AND SEISMIC WAVES , GRL,2010.
P. Favreau; A. Mangeney; A. Lucas, N. M. Shapiro; G. B. Crosta; F. Bouchut ; O. Hungr,Numerical modeling of landslide generated seismic waves. AGU 2009.

Behavior & Mobility of Large Martians landslides

Landslides take part in weathering and transport processes on Earth as well as on Mars. Prediction of their dynamic remains awkward in spite of many experimental and numerical studies. Numerous numerical works have been carry out on real landslides cases using DTM (Digital Topographic Model) so as to improve our understanding of the behavior by comparing results with field observations. Generally, previously studies are based on runout analysis dealing with mean dissipation calibration such as friction coefficient. Nevertheless, the shape of the initial scarp is generally unknown for real cases. It is perilous in this context to get good predictions of spreading in a given geological setting. We thus tried here to clear up the potential error on mean dissipation because of the uncertainty related to the unkown geometry of the initial scarp. In addition, from the field observations of final stage (e.g. landslide's deposits) we tried to get feeback on initial conditions such as geometry and volume of mass involved. This study is focused on the effect of the scarp geometry on the spreading flow using a numerical model able to take into account the curvature matrix of the bottom topography. Using these capabilities, a benchmarking analysis involving theorical scarp geometries (e.g. 2D and 3D) have been performed. We then combined a geomorphological analysis on real cases. Our results show that the runout distance is not affected by the initial shape of the scarp, whatever the friction coefficient. Otherwise, we observed on 3D tests that the shape of the final deposits is a function of the scarp geometry. As consequences, from final deposits, we are able to get information on both, initial geometries and initial volume involved in the mass spreading. We validated these results with terrestrial examples for which the scarp geometry and friction coefficient are well known. then, as from these results, we tried to apply a feedback analysis on Martian landslides. We get good agreement between geomorphological analysis and modeling, allowing us to explore deeper in initial conditions of landslides on Mars. As conlusions, we developped a feedback analysis process able to give information on volume and shape of the initial mass involved in landslides.