The role of topographic amplification effects on the generation of earthquake-induced rock slope failures

摘要

Landslides are an important consequence of strong earthquakes. However, standard approaches to assess landslide hazard rarely consider site effects such as topographic amplification. Rock slides and falls triggered by the 1994 Northridge earthquake in California and the 1999 Chi-Chi earthquake in Taiwan have been investigated to study the influence of topographic amplification of the ground motion on the seismic instability of rock slopes. The failures were triggered on steep slopes and in dry conditions, and are located in key areas of characteristic geomorphology where an increase in landslide density was observed compared with adjacent areas. Slope stability analyses suggest that local amplification of the strong motions was required to trigger most of the landslides. The study highlights the need to consider topographic amplification effects for hazard assessment of seismically induced landslides. Current limitations in the predictability of topographic effects are also discussed in the context of the investigated case studies.