Nonlinear Site Response Effects on the Standard Deviations of Predicted Ground Motions

Soil nonlinearity has been widely accepted for the estimation of median ground motion, but its effects on the ground-motion standard deviations have not. In particular, the impact of soil nonlinearity on the interevent standard deviation of predicted ground motions has been misunderstood. In this article, we show that, for the prediction of ground motions on soil site conditions, both the intraevent and interevent standard deviations are impacted by soil nonlinear response. We also present the various approaches for accounting for soil nonlinearity in the variability of predicted ground motions.