Evaluation of Liquefaction Potential in Memphis and Shelby County

Keywords: Liquefaction, New Madrid Seismic Zone (NMSZ), Memphis, Tennessee, Shelby County, Tennessee, Lifeline Systems, Water Delivery Systems, Seismic Performance, Post Earthquake Fires, Computer Programs, and Earthquake Engineering.

Abstract: This report summarizes the methodology and results of evaluation procedures for soil liquefaction potential in Memphis and Shelby County, Tennessee. Twenty-two representative sites were selected where appropriate geotechnical data had been collected, and a parametric study was performed by computer simulation of 53 earthquake acceleration-time records covering peak bedrock accelerations of 0.08 to 0.35 g. The dominant frequencies and durations of shaking were chosen to be consistent with earthquakes of 6.5 and 7.5 M in the New Madrid seismic zone. Stress and pore pressure response at the representative sites were analyzed with the computer programs MASH and APOLLO. Liquefaction susceptibility at each site was determined by means of liquefaction index criteria which account for soil type, drainage conditions, Standard Penetration Test values, and peak bedrock accelerations. Liquefaction potential maps for Memphis and Shelby County are developed for 6.5 and 7.5 Mw earthquakes in the New Madrid seismic zone on the basis of the liquefaction index. The potential for structural damage because of soil liquefaction is discussed.