Classification of large-scale landslides induced by the 2008 Wenchuan earthquake, China

Over 30,000 landslides were triggered by the 2008 Wenchuan earthquake. The deformation and failure mechanisms of these landslides have been found distinct from those of general landslides self-weight induced. Under gravity, typical sliding in rock slope commonly occurs along a gentle tension crack in some depth at the rear part, which connects to a shear plane at the lower part of the slope to form a complete failure surface. However, due to seismic shaking, a much deeper and steeper tension crack tends to develop at the rear part, which promotes the shearing at the far lower part of the slope. In this paper, the failure modes of earthquake-induced landslides have been classified into four scenarios, in terms of failure mechanisms, characteristics of geological structures, and development of the sliding surface, i.e., tension-strike slipping, tension-dip layering, tension-shattering, and tension-shearing failures. This is evidenced by field investigations. Detailed field investigations were performed on the deformation and failure characteristics of large-scale and deep-seated landslides induced by the Wenchuan earthquake, among which five typical landslides are introduced in this paper in order to illustrate the classification.