Triggering Factors Susceptibility of Earthquake-induced Collapses and Landslides in Wenchuan County

Abstract

The remote sensing image and survey results after the earthquake showed that,the Wenchuan Ms8.0 Earthquake had induced more than 5 528 collapses and landslides in the Wenchuan County with the area of about 4 083 km2.Based on GIS,the statistical relationships between the collapses and landslides distribution and the factors,such as the lithology,distance to faults,slope gradient,elevation and others,were analyzed.Susceptibility of triggering factors of Wenchuan Earthquake was analyzed by the means of slope certainty factors(CF).The most numerical intervals of each factor which are inclined to hazards were determined.The results showed that the hazards mainly distributed in the stratum of Proterozoic,Sinian and Permian with hard rock,in the slope of more than 40 degree,within a 10 km buffer zone to the active faults and 6 km to the no active faults.The collapses and landslides distributed mainly in the area with the elevation 1 000 ~ 2 500 m and relative height between 600 ~ 1 000 m.The mainstream of the Min River absolutely controlled the hazard distribution.The conclusions indicated that the factors have the effect of seismic wave propagation in media and distance effect.There is significant different numerical interval which inclined to collapses and landslides in lithology and slope between induced by earthquake and by rainfall.