Screening evaluation of seismically induced displacement of landslides

Abstract This article describes the rationale employed by pseudostatic and Newmark techniques to evaluate seismic slope stability, then compares the results obtained from pseudostatic and Newmark rigid block analyses and compares these with the Simplified Seismic Design Procedure proposed by Bray et al. A step-by-step explanation of the Simplified Seismic Design Procedure is presented, using the 1998 Mission Peak Landslide in Fremont, California as a case study. The Simplified Seismic Design Procedure is a useful tool for screening analyses of landslides to estimate the gross permanent displacement following seismic shaking. This screening technique uses basic physical parameters and published charts, which can be applied to cohesive or cohesionless soils. It can be employed with little expense to provide an estimate of the seismically-induced permanent displacement. This allows an approximate comparison of those slopes that likely pose low, medium, or high risks for damaging movement. In 1998, a permanent displacement between 1 m and 2 m was generally considered acceptable for cohesive embankment dams or levees. Calculated deformation of more than 1–2 m may require more rigorous analysis, modeling the dynamic system using nonlinear analytical techniques.