Abstract

We develop a regional site‐effects model for central and eastern North America based on an analysis of the residuals of observed ground‐motion parameters relative to two regional ground‐motion prediction equations: one model has a hard‐rock (site class A) reference site condition, whereas the other is referenced to a B/C boundary site condition (site classification of National Earthquake Hazard Reduction Program). In both cases, the residuals are well described by a site‐effects model based on site fundamental frequency fpeak, in which fpeak is as determined from the horizontal‐to‐vertical component response spectral ratios. Accordingly, we derive an fpeak‐based site amplification model with respect to B/C and hard‐rock reference site conditions. Implementing the fpeak‐based model, we reduce random variability in amplitudes σ by 10% on average, for a selected database from the Next Generation Attenuation‐East Project, relative to the value obtained when using a generic site‐effects model parameterized by near‐surface shear‐wave velocity (time‐averaged shear‐wave velocity in the upper 30 m, VS30). The reduction in σ comes from the site‐to‐site component of the variability forumla (reduced by 20% on average), whereas the single‐station variability forumla is unaffected.

You do not currently have access to this article.