Density distribution of landslides triggered by the 2008 Wenchuan earthquake and their relationships to peak ground acceleration

The distribution of landslides induced by the 2008 M_w 7.9 Wenchuan earthquake was investigated following the method of Meunier et al. (2007) to examine the relationships to peak ground acceleration (PGA). Results suggest that landslide densities are quantifiably related to PGA. Thresholds of PGA_cr for landslide failure are 0:21g for average horizontal PGA and 0:12g for average vertical PGA. As with other earthquakes, the distribution of the Wenchuan earthquake-triggered landslides can be described by two equations, based on area and source densities, respectively. The similar damping factors of ~20 in these two equations suggest that both density distribution patterns of landslides reflect the dissipation of seismic energy. Landslide-derived PGA equations were then produced for the hanging-wall region of the earthquake-affected area. The results indicate that it should be possible to produce an earthquake shake map from the distribution of earthquake-triggered landslides in an area where there are few or no seismic instruments but many landslides.