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In this study, Material Point Method (MPM) is improved to simulate coseismic slope stability and liquefaction-induced embankment failure under earthquake loading. First, by using elastic or elastoplastic models, topographic amplification and different slope failure modes are analyzed considering the effects of slope geometry, soil properties and excitation frequencies etc. The MPM model is then applied to predict a cascading slope failure process, including triggering, shear band formation, runoff and final deposition. Finally, a fully nonlinear bounding surface soil model is implemented in the two-phase soil-water coupled MPM framework to investigate the liquefaction mechanism and associated dam failure using two case histories. The numerical results are generally comparable with the post-failure profiles obtained from field investigation, which highlight the advantage of MPM in handling liquefaction-induced large deformation. The MPM shows great promise to quantitatively assess risk and consequence associated with seismic slope failure and soil liquefaction, thereby, advance the performance-based engineering design and analysis.

Earthquake-induced landslides are one of the most catastrophic effects of earthquakes, as evidenced by many historic events over the past decades, such as the 1994 Northridge earthquake in California and the 2008 Wenchuan earthquake in China. Realistic prediction of coseismic landslides is crucial for the design of key infrastructure and to protect human lives in seismically active regions. To date, analytical methods for estimating coseismic landslides have been based on highly simplified models. In this study, an integrated Spectral Element Method (SEM)-Newmark model is developed to directly simulate three-dimensional wave field in complex topography on a regional scale, while the associated landslide is indicated by the Newmark sliding displacement analysis considering key model factors. Topographic amplification, soil response, near-field characteristics of earthquake shaking and hydrogeological conditions can be simulated, and their effects on coseismic landslides are studied. In this paper, two regional-scale case studies were conducted using the developed SEM-Newmark model, including landslide hazard assessment for natural terrain in the western part of Hong Kong island, and the massive landslides occurred during the 2014 M6.5 Ludian earthquake in China. These case studies demonstrated that the proposed integrated model can be effectively used for regional-scale coseismic landslide hazard assessment under various earthquake scenarios and hydrogeological conditions.