Liquefaction Potential Map for Charleston, South Carolina

Abstract

The liquefaction potential of saturated cohesionless deposits in Charleston, South Carolina, was evaluated probabilistically. The map is a combination of liquefaction susceptibility and liquefaction opportunity. Critical acceleration, the measure of liquefaction susceptibility, was obtained using the simplified empirical method developed by Seed and his coworkers. This method is based on the empirical relationship between standard penetration resistance and cyclic stress ratio. The liquefaction opportunity is determined by modeling zones of different seismic threat. The probability of liquefaction is computed by comparing the acceleration at the site to that required to cause liquefaction. Results are expressed as maps of zones of different risk levels and through a normalized liquefaction resistance index of the probability of liquefaction. Over 200 boring logs from peninsular Charleston were examined, showing the soil variability in the study area. This variability is due to the large amount of filling that took place over 300 years to reclaim land from the sea, swamps, and creeks that covered much of the original peninsula. The results indicate peninsular Charleston has a moderate liquefaction potential.