Susceptibility analysis of earthquake induced landslide-dam based on GIS

Some significant hazards may occur due to large landslide-dams formed by earthquake induced landslides. It presents serious threats to both life and property from possible upstream flooding as the impounded lake water level rises, possible dam failure and downstream flooding as rapid release of impounded water. In order to prevent those secondary disasters, we made an assumption that the landslide dam is only formed when a large amount of landslide deposits directly rush into a river with moderate or high-velocities, and then presented a practical prediction method to extract the dangerous slopes as sources of earthquake induced landslide-dam formation. The prediction procedure consists of the following steps: (1) Identification of all the slopes using spatial statistics; (2) The extraction of potential slopes according to our assumption using three spatial relation filters; (3) Stability analysis to determine landslide prone slopes and volume estimation of potential landslide deposits using Limit Equilibrium Analysis. (4) Production of susceptibility map by ranking the exact slopes. This method has been used to extract slopes those have potential to collapse and form landslide-dams in the catchment of Tongkou river based on the data from 2008 Wenchuan earthquake. The results show that the proposed method is effective and efficient.