Wind control of storm-triggered shallow landslides

Heavy rainstorms are a major control of shallow landsliding in mountainous areas. The influence of three-dimensional (3-D) variability of precipitation is analyzed by coupling a fine-resolution atmospheric model (RAMS) with a fine-resolution topographic model (DEM) to represent the 3-D precipitation flux generating the catastrophic flood that occurred in Versilia, central Italy, on 19 June 1996. Matching of this flux with the observed scars and debris shows that 92% of the mass movements occurred where the normalized precipitation flux exceeds 0.80 and less then 2% where this is null. These results give an insight of the detected role of exposure in explaining the spatial variability of observed landslides as emerging from multivariate statistical analysis. The interaction of the wind-driven precipitation field with topography is an important control of shallow landslides triggered by convective storms in upland catchments.