Empirical Linear Seismic Site Amplification in Central and Eastern North America

We present empirical linear site amplification models conditioned on time‐averaged shear wave velocity in the upper 30 m ( V S 30 ) for central and eastern North America. The models are derived from ground motion data and site condition information from the NGA‐East project and are intended for use with reference rock ground motion models. Site amplification is found to scale with V S 30 for intermediate to stiff site conditions ( V S 30 > 300 m/s) in a weaker manner than for active tectonic regions such as the western United States. For stiff sites ( > 800 m/s), we find differences in site amplification for previously glaciated and nonglaciated regions, with nonglaciated sites having lower amplification. The models were developed using a combination of least‐squares, mixed effects, and Bayesian techniques; the latter show that accounting for predictor uncertainty does not appreciably affect the median model but decreases model dispersion. Our V S 30 ‐scaling models are modular and additive to simulation‐based models for the nonlinear components of site response. A limitation of the present models is that they do not account for site‐specific resonance effects.