Simplified Procedure for Estimating Seismic Slope Displacements for Subduction Zone Earthquakes

Seismic slope displacements are estimated for earth structures or natural slopes subjected to interface earthquakes in subduction zones. The fully coupled, nonlinear seismic slope displacement model captures the important influence of the system’s yield coefficient ky, its initial fundamental period Ts, and the ground motion’s spectral acceleration at a degraded period of the slope taken as 1.5Ts. The model separates the probability of zero displacement (i.e., <0.5 cm) from the distribution of nonzero displacement, so that low values of calculated seismic displacement do not bias the results. The input ground motion is the primary source of uncertainty in assessing seismic performance of an earth slope or system. Thus, a comprehensive database containing 810 two-component ground motion recordings from subduction zone interface earthquakes was developed and used to compute seismic slope displacements. The resulting model provides seismic displacement estimates similar to those from the previous model that was developed using shallow crustal earthquakes along active plate margins, but there are a few important differences. The subduction zone earthquake-induced slope displacement model can be implemented rigorously within a fully probabilistic framework or used deterministically to evaluate seismic displacement potential.