ABSTRACT
Earthquake-induced settlement in sand deposits and lateral movement of slopes due to an underlying failed sand layer are the major damaging effects on structures resulting from either consolidation of unsaturated sand or liquefaction of saturated sand. Memphis is an important metropolitan area in Tennessee, USA, located within 40 miles south of the new Madrid seismic zone (NMSZ) in the central USA. Granular sand layers overlain by a layer of surficial clayey soils (silty to sandy clay) or loessial soils (clayey to sandy silt) are present throughout the Memphis area. In general, the surface of these sand layers are located at a depth as shallow as 10 feet to more than 40 feet with thickness ranging from about 5 feet to greater than 40 feet. In this study, earthquake-induced earth movements are estimated on the basis of engineering boring logs, previous seismic hazard and theoretical earth movement analyses, and on results of field observations of foundation failures and lateral slope movements following past earthquakes. The average and possible range of earth movements corresponding to assigned liquefaction risks are shown in a series of earth movement potential maps. Liquefaction mitigation techniques are also briefly discussed.
