Development of Regional Seismic Slope Analysis Model Based on the Cases of Chi-Chi Earthquake

In 1999, the Chi-Chi earthquake caused numerous landslides and tremendous loses in central Taiwan. It becomes essential to produce the earthquake induced landslide potential map for hazard mitigation in Taiwan. To determine such landslide potential, the permanent displacement appears to be a reasonable parameter for calibration of potential. However, the overall measurement of landslide displacement is very complex. The crustal deformation can be observed through InSAR analysis, which provides displacement data for further analysis. The model slope shaking table tests were performed to observe seismic slope behavior and then analyzed with proper numerical analysis. In the analysis, the equation proposed by Hardin and Drnevich (1972) is used to find the failure plane and to simulate the amplification effect with parameter reduction. The particle image velocimetry analysis was also conducted to study the evolvement of slope displacement, which provides a different perspective and helpful point of view in landslide displacement analysis. The numerical analysis provides a method to establish the failure plane of landslide and can be applied to the prototype slope in field. Thus the slope in the field can be analyzed through the method developed. Finally, a regional seismic slope analysis model was developed based on Newmark’s displacement. The proposed depth-length ratio method provides reasonable value of landslide failure depth. The threshold of landslide 5 cm is adopted and which will turn in a prediction rate of 94% for the study area.