Applications of non-ergodic site response in ground motion modeling

Site-specific (non-ergodic) seismic hazard analysis is increasingly being employed as part of ground motion hazard characterization for critical projects. Non-ergodic site response can be evaluated from the interpretation of ground motions recorded at (or near) the site or from simu-lations. The simulation method that is most frequently employed is ground response analysis, which can capture impedance, resonance, and nonlinear effects for vertically propagating shear waves. Such effects are often large contributors to site response, but are not sole contributors, as other effects related to basin geometry can also be influential, particularly at long oscillator periods. We review procedures for conducting ground motion hazard analysis using non-ergodic site response models, including aleatory variability and epistemic uncertainty. We de-scribe preliminary new work related to spatial correlation of site response that is important for some applications. The challenges and benefits of applying these procedures are illustrated through case histories in California, Italy, and Japan