COMPARISON OF DISTRIBUTION OF LANDSLIDES TRIGGERED BY WENCHUAN, LUSHAN, AND LUDIAN EARTHQUAKES

All of the M_S8.0 Wenchuan, M_S7.0 Lushan, and M_S6.5 Ludian earthquakes have triggered a large number of landslides. Due to differences in magnitude, geology, and topographical conditions, the distribution of seismic landslides vary widely. In this study, existing research results are combined to perform a contrastive analysis of seismic landslide distribution patterns based on three aspects:earthquake characteristics, geology, and topography. The following results are obtained. (1) The number and density of landslides due to the three earthquakes increase with the increase of peak ground acceleration(PGA) and magnitude. The number of landslides shows an increasing trend following an increase of intensity during the Wenchuan and Ludian earthquakes. However, the area affected by the relatively low-intensity Lushan earthquake also develops numerous landslides. (2) The maximum distance of influence of a geological fault on landslide distribution increases with the increase of magnitude. Within the range of 0.2 times of the maximum distance of influence, the Wenchuan earthquake has an 80% landslide distribution, whereas the other two earthquakes have only 30%. Moreover, the number of landslides decreases exponentially with distance of the Wenchuan earthquake from geological faults. (3) The distribution of seismic landslides is strongly influenced by topography. In the Ⅶ or higher intensity regions, the relief depth increases and earthquake-triggered landslides in high concentration areas have relatively higher relief. Furthermore, the slopes gradient with concentrated landslides can subsequently increase. Seismic landslides occur more frequently along mountain ridges and deep slopes in areas of higher relief, which may be related to the topographic amplification effect.