Liquefaction-induced ground failures are a major cause of damage during earthquakes. An important step in minimizing this damage is to identify sites that are susceptible to liquefaction by making in situ measurements of soil properties related to excess pore pressure development. Existing methods of site investigation are unable to characterize a site completely because measurements are made at discrete locations only; the spatial variability of soil properties has to be inferred by other methods. The objective of the first phase of this project is to develop and implement seismic geotomography to obtain a more complete characterization of sites susceptible to liquefaction. In seismic geotomography, a mass of soil is traversed by a large number of seismic waves to measure the vertical and lateral variability of the initial tangent shear modulus (a parameter used for liquefaction susceptibility evaluation). The objective of the second phase is to apply seismic geotomography at a site in the Charleston, South Carolina, seismic zone so as to compare geotomography with conventional site characterization techniques, such as the standard penetration test (SPT) and the cone penetration test (CPT). Soils susceptible to liquefaction are known to exist in this area.
