Geotechnical Issues and Site Response in the Central U.S.

Abstract

This article highlights the results of recent studies dealing with key seismic geotechnical issues in the central United States including: 1) Significance of using the Conditional Mean Spectrum for seismic design at the periphery of the New Madrid seismic zone: The commonly used Uniform Hazard Response Spectrum does not represent any specific earthquake event in this region whereby the seismic hazard is a composite of two or more distinct sources of significantly different characteristics. Treatment of these sources separately results in a more realistic assessment of seismic hazard. 2) Site response of deep soil deposits in the Mississippi Embayment: there is a need to use depth-dependent site amplification factors instead of commonly used depth-independent NEHRP site coefficients. 3) Unique aspects of liquefaction in the central United States, particularly in the New Madrid Seismic Zone: Currently used liquefaction triggering analysis has been developed for plate margin settings which differ from the tectonic setting in the central United States.