GIS PLATFORM AND CERTAINTY FACTOR ANALYSIS METHOD BASED WENCHUAN EARTHQUAKEINDUCED LANDSLIDE SUSCEPTIBILITY EVALUATION

At 14：28(Beijing time)of May 12, 2008,a catastrophic earthquake with surface wave magnitude of 80 struck Sichuan province of China. Tens of thousands of landslides were triggered by this earthquake over a broad area. A total of 48007 landslides were interpreted from aerial photographs and multisource remote sensing imageries,verified by field check. A spatial database,including landslides and associated controlling parameters which may have influence on the occurrence of landslides,was developed and analyzed using geographical information system(GIS)technology. The eight factors that influence landslide occurrence,including seismic intensity,lithology,slope angle,faults,elevation,slope aspect,drainages and roads were created in raster data format base on GIS platform. The landslide susceptibility index of all ranks in each impact factor was calculated,using the certainty factor analysis method. Earthquakeinduced landslide susceptibility areas of 16 impact factor combination categories were analyzed and mapped one after another,using the GIS raster analysis methods. The susceptibility result of the highest AUC(Area Under Curve)was used to create susceptibility map by using Natural Breaks law. The resulting susceptibility map showed five classes of landslide susceptibility,ie.〖KG-*5〗,extremely high,high,moderate,low,and extremely low. The validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide distributions. The area with extremely high and high susceptibility accounts for about 1169046 km2, 2402% of the study area,includes landslide areas of 52484 km2, 7373% of all landslide areas. The susceptibility success accuracy was up to 82107% in the form of AUC．