**3.3 Relationship between landslide and individual causative factor**

More than fifty factors can be considered as the landslide causative factors (Lin, 2003). By considering the data availability, analysis effectiveness, and independence of each factor (Lee et al., 2008), we selected the follow 8 factors: slope gradient, elevation, slope range, slope aspect, specific catchment area, lithology, distance to the fault and distance to the stream, to examine the causative factors contributing to the initiation of landslides.

Each causative factor was classified into several categories. The number of the slope units in each category is calculated and the percentage of the category among the whole slopes is given in Fig.9(b). For each category, the percentage of the failure slopes among the slopes in the same category is given as the landslide frequency in Fig. 9(a).

A total of 55,899 slope units were indentified in Qingchuan County (Fig. 8). They will be

The basic data include a 1:100,000 geological map and a 10m grid digital elevation model (DEM) made from the available topographic map with 5m contour line interval. 885

More than fifty factors can be considered as the landslide causative factors (Lin, 2003). By considering the data availability, analysis effectiveness, and independence of each factor (Lee et al., 2008), we selected the follow 8 factors: slope gradient, elevation, slope range, slope aspect, specific catchment area, lithology, distance to the fault and distance to the

Each causative factor was classified into several categories. The number of the slope units in each category is calculated and the percentage of the category among the whole slopes is given in Fig.9(b). For each category, the percentage of the failure slopes among the slopes in

stream, to examine the causative factors contributing to the initiation of landslides.

landslides were identified from field investigations and RS results.

the same category is given as the landslide frequency in Fig. 9(a).

**3.3 Relationship between landslide and individual causative factor** 

used for landslide susceptible analysis in this study.

Fig. 7. Location of the study area

Fig. 8. Slope unit division of Qingchuan area

From the statistical analysis, the following results can be found.

