The Spatial Distribution and Attribute Parameter Statistics of Landslides Triggered by the May 12th,2008,MW7. 9 Wenchuan Earthquake

A complete landslide inventory and attribute database is the importantly fundamental for the study of the earthquake-induced landslide.Substantial landslides were triggered by the M7.9 Wenchuan earthquake on May 12,2008.Google Earth images of preand post-earthquakes show that 52 194 co-seismic landslides were recognized and mapped,with a total landslides area of 1 021 km~2.Based on the statistics,we assigned all landslide parameters and established the co-seismic landslides database,which includes area,length,and width of landslides,elevation of the scarp top and foot edge,and the top and bottom elevations of each located slope.Finally,the spatial distribution and the above attribute parameters of landslides were analyzed.The results show that the spatial distribution of the co-seismic landslides is extremely uneven.The landslides that mainly occur in a rectangular area(a width of 30 km of the hanging wall of the Yingxiu-Beichuan fault and a length of 120 km between Yingxiu and Beichuan) are obviously controlled by surface rupture,terrain,and peak ground acceleration.Meanwhile, a large number of small landslides(individual landslide area less than 10 000 m~2) contribute less to the total landslides area.The number of landslides larger than 10 000 m~2 accounts for 38.7 % of the total number of co-seismic landslides, while the area of those landslides account for 88% of the total landslides area.The 52 194 co-seismic landslides are caused by bedrock collapse that usually consists of three parts:source area,transport area,and accumulation area.However,based on the area-volume power-law relationship,the resulting regional landslide volume may be much larger than the true landslide volume if the landslide volume is calculated using the influenced area from each landslide.