Implications of Eastern Ground‐Motion Characteristics for Seismic Hazard Assessment in Eastern North America

There has been much recent work on the nature of ground motion in eastern North America (ENA).'-3 This has led to a new understanding of ENA ground motions, and in particular how they differ from better-observed western North American (WNA) ground motions.4 These differences in characteristics, combined with those in the occurrence rates of earthquakes, have important implications for seismic hazards in eastern North America. The purpose of this paper is t o review the salient features of ENA ground motions and their implications for seismic hazard in simple engineering terms. Illustrative examples show typical expected response spectra for probability levels relevant to building codes and critical facilities. Conclusions are drawn a s to how seismic hazard in ENA differs from that in the more active western regions.