Recent Trends in Ground Motion and Spectral Response Relations for North America

Recent ground motion relations which predict pga, pgv and psrv for rock sites in ENA are based on a stochastic model whose parameters are indicated by seismological studies of earthquake source and attenuation processes. The validity of the model is verified by application to WNA. The choice of model parameters is validated by comparison of model predictions with ground motion data for ENA. For any magnitude, near-source ENA ground motions are enriched in high frequencies relative to WNA motions. This causes eastern pga values, and psrv values for frequencies greater than 10 Hz, to be greater than their western counterparts. For psrv at frequencies less than 10 Hz, median near-source ground motions in ENA are roughly comparable to those in WNA. Eastern ground motion characteristics have important implications for seismic hazard. High frequency structures in many parts of ENA face a hazard comparable to that in many active areas of California, whereas the hazard for low-frequency structures on rock sites in ENA is relatively modest.