Spatial distribution of landslides triggered by the Wenchuan Ms 8.0 earthquake near the epicenter

Abstract

The 2008 Wenchuan earthquake (Ms = 8.0) occurred in Sichuan, China, and triggered many landslides that were more concentrated near the epicenter. A watershed of Min River of length 80 km and an area of approximately 2100 km2 was chosen in this study to assess the spatial distribution of the co-seismic landslides. Both the widely used indexes, including co-seismic landslides number (LN) and landslide concentration (LC), and two new indexes, slope pixel percentages (SPP) and landslide pixel percentages (LPP), are used to make correlation analysis with topographical factors. The SPP is defined as the pixel percentage of topographic factors related to the entire study area on pre-earthquake digital elevation model. The difference between the SPP and LPP is that the latter is only considered in the area where co-seismic landslides occur. The main results of this study are: (1) The distance from surface rupture (rf) leads to a better correlation with LC; (2) greater than one twice of the landslides that occur on the west side of the Min River line; (3) the distribution of the landslides in our study area shows a larger average distance to fault rupture comparing to the average value in the total Wenchuan earthquake; (4) the most remarkable correlation found is with the topographic aspects and the fault thrusting direction.