International audienceMany tools have been developed to manage rockfall risk. In particular, many softwares are designed to simulate rockfall trajectories. These softwares require the definition of many parameters, especially those describing the mechanical properties of soils (rigidity, roughness, etc.). Choosing appropriate values for these parameters remains a difficult task and will depend on the expert know-how. Here, we propose a simple method that can be used routinely to evaluate the relative influence of these parameters (about 50 parameters for the examples below) on the simulation results. The objective is 1) to identify the parameters that are playing a key or predominant role in the simulations and that require additional characterization efforts, 2) to estimate the uncertainty that exists on the simulation results. The application cases for this sensitivity analysis are two busy roads on Reunion island (France) when considering the residual rockfall risk after a major rockfall event
