A Seismic Site-Amplification Map for Memphis, Shelby County, Tennessee From Geophysical, Geotechnical, and Geological Measurements

As a part of the U.S. Geological Survey’s (USGS) Memphis, Shelby County Seismic Hazard Mapping project, geophysical and geotechnical subsurface data are being collected into a subsurface database for Shelby County, Tennessee. Memphis is a major urban area near the New Madrid Seismic Zone in the central U.S. and has a building stock that is largely vulnerable to even moderate ground shaking from earthquakes. The subsurface geological, geotechnical, and geophysical information gathered will be used to construct a three-dimensional model of the geology and seismic velocity structure of the area down to Paleozoic bedrock (up to 1 km deep) for the purpose of determining site amplifications. The resulting characteristic seismic velocity profiles will include variability in S-wave velocity with depth and will be used to provide the uncertainty estimates in site amplification measurements. The mean site amplification map for Shelby County will serve as an amplification potential map for use in the seismic hazard assessment portion of the project.