Dynamic mechanisms of earthquake-triggered landslides

Earthquake-triggered landslides usually cause great disasters, and yet their dynamic mechanisms remain poorly understood. This paper will derive a general conceptual landslide model from the geometric and kinematic features of the most landslide masses triggered by the 2008 Wenchuan earthquake. Kinematic characteristics and dynamic processes are simulated here by means of finite element method (FEM) based on the dynamic process of the discontinuous deformable body. The calculated results presented the whole course of landslide motion, and displayed some typical kinematic characteristics such as initiation, sliding, ejection, collision, flying in the air, and climbing of landslides. The simulation result also shows that, under combined seismic inertial forces and gravity, landslides will start to slip once it overcomes the friction between the sliding mass and slip-bed, then it will move from slow to fast along the slippery bed until it ejects from the slip-bed. Moreover, the high frequencies and serious damages by landslides in the Wenchuan earthquake are caused by the strong ground motion on the mountain slopes in and around the epicenter that was dramatically amplified owing to both resonances produced by the seismic event and topographical amplification by seismic motion. In addition, the modeling results suggest that the direction, amplitude, frequency, and duration of strong ground motion have a great influence on the stability of landslide mass. Therefore, the study helps us better understand dynamic mechanism of landslides, seismic hazard assessment, and dynamic earthquake triggering.