The factors related to shallow slope failures include soil depth, vertical soil structure, and bedrock topography. In this study, we surveyed spatial variations of soil depth and vertical soil structure by conducting simplified penetration tests, and then estimated bedrock topography in a newly-planted hillslope. We analyze the ability of these three factors to detect potential slope failure locations (PSFL) on the basis of information from a shallow slope failure which occurred at the study site during the survey period. The results show that soil depth varies spatially on the hillslope. However, there are no obvious correlations between soil depth and any topographic factor.This finding differs from the results suggesting an inverse correlation between soil depth and slope in some previous studies. Comparing the three factors, the area of PSFL determined by soil depth is the smallest. This implies that soil depth plays an important role in predicting the potential of a shallow slope failure. According to information about
vertical soil structure, we presume that vertical rainwater infiltration is impeded by local hard soil layers, rocks, and the soil-bedrock interface, and following increase of pore water pressure might trigger shallow slope failure. This indicates that vertical soil structure has implications for vertical soil water movement and PSFL. Consequently, we
suggest that the spatial variations of soil depth and vertical soil structure should be carefully considered when assessing potential locations for shallow slope failures in Taiwan.
Key Words : Bedrock topography, shallow landslide, soil depth, vertical soil structure.