Study of Site Response at a Selected Memphis Site

Keywords: New Madrid Seismic Zone (NMSZ), Memphis, Tennessee, Design Earthquakes, Geotechnical Studies, Site Amplification Studies, Ground Motions, Synthetic Bedrock Accelerograms, Hard Rock, Shake, Soft Rock, Near-Surface Soil Profiles, Shelby County, Tennessee, Equivalent Linear Analysis, DYNA1D, Nonlinear Inelastic Analysis, and Computer Programs.

Abstract: The influence of geological and geotechnical factors on potential ground motions in Memphis due to a 65 km distant hypothetical Mw= 7 New Madrid earthquake was investigated. From the study of the seismotectonic environment and the seismicity of the region, the characteristics of the design earthquake are selected. A seismological model of the radiation/attenuation of the earthquake source and generated waves is used to generate synthetic bedrock (hard rock) accelerograms, which are then propagated through a deep deposit of soft rock to obtain input base excitations for the near-surface soil profiles. A representative soil profile for Memphis is selected from a large number of borelog data. Propagation of the seismic waves through this soil profile is modeled to obtain the seismic motions at the ground surface. Effects of nonlinear inelastic versus equivalent-linear analysis has been investigated. Results are presented in the form of site-specific response spectra and a proposed design spectrum.