April 2026: Seismic Slope Displacement Procedures Webinar

Seismic slope stability is a major consideration in evaluating the performance of dams. The seismic slope displacement calculated with sliding block models provides a valuable index of the seismic performance of water-retention and tailings dams. The specific features of each sliding block method determine its reliability. Rigid sliding block models should not be used except for the limited case when the sliding mass is rigid. A calibrated, coupled nonlinear deformable stick-slip sliding block model calculates reasonable values of seismic slope displacement.

The primary source of uncertainty in assessing the seismic performance of a dam that will not undergo a liquefaction-induced flow failure is the input earthquake ground motion. Hence, many ground motion records for each tectonic region should be used in the evaluation. Seismic slope displacement depends primarily on the earthquake ground motion’s spectral acceleration at the effective fundamental period of the potential sliding mass and its duration of strong shaking, as well as on the dam’s yield coefficient.

The pseudostatic slope stability method can be used as a screening analysis if the seismic coefficient is selected to capture the seismic demand and is calibrated to be consistent with the tolerable amount of seismic slope displacement. Calibrated, coupled nonlinear sliding block models enable the sensitivity of the calculated seismic slope displacement and its uncertainty to key input parameters to be assessed. These procedures can be implemented within a performance-based design framework to estimate the seismic slope displacement hazard.