Catastrophic landslides associated with the M8.0 Wenchuan earthquake

Numerous earthquake-induced landslides occurred in the Longmenshan tectonic belt associated with the 12th May 2008 Wenchuan earthquake where the vertical acceleration was greater than the horizontal ground motion. Many of these landslides originated in the steep mountain terrain which amplified the effect of the ground shaking. Three typical landslides are discussed: the Niujuangou sturzstrom, the Chengxi rock slide and the 1,100 million m3 Daguangbao rock slide. Having discussed the individual slides and some previously published models, a mechanism to explain both the very fast velocity of the slides and their long run-out distance is proposed, taking into account aerodynamic principles. The model postulates that air trapped in the steep-sided valley by the collapsing rock mass forms a “cushion-effect” on which the debris moves.