Seismic landslide hazard assessment - observational and analytical approaches

This paper is concerned with seismic landslide hazard assessment, both site specific and regional. Recent studies and applications are cited in order to explore the role of empirical, analytical, probabilistic and observational approaches. The role of GIS-based methods and techniques for seismic landslide hazard mapping is highlighted. Comparison is made with the on-going developments with regard to methods for the assessment and management of rainfall-triggered landslides. In particular, attention is drawn to the hazard-consequence matrix approach. The development and use of a similar approach would be relevant to issues concerning risk management of seismic landslides. Attention is drawn to potentially important research directions. The importance of seismic landslide hazard assessment is widely recognized. Significant progress has already been made in developing suitable methods of analysis for individual sites. These include methods of stability analysis based on the concept of limit equilibrium, more advanced approaches as well as sophisticated methods for estimating slope deformations. Because of the importance of uncertainties, suitable methods of probabilistic modeling have also been developed. GIS-based approaches have proved useful and effective for regional studies and for developing seismic landslide hazard maps. So far, only relatively simple analytical methods have been used as a basis for such mapping. The feasibility of using more sophisticated methods within a GIS-environment must be explored .The validation of hazard maps is facilitated by the use of reliable historical and observational data. Long-term surface and sub-surface monitoring can prove useful for further validation with the passage of time. Updating hazard maps after each significant earthquake will be feasible if such monitoring systems are in place. Existing systems may have been designed and installed for monitoring rainfall-triggered landslides. Therefore it is vitally important to reassess their suitability for slope performance under seismic conditions