Assessment of liquefaction hazards in Charleston quadrangle, South Carolina

In this paper an improved method for evaluation of liquefaction hazard is presented. The liquefaction potential index developed by Iwasaki and his co-workers is modified using the concept of probability. The modified liquefaction potential index is then calibrated with field observation data, which yields an empirical equation for the probability of liquefaction-induced ground failure. The method and procedure is then employed to study the ground shaking level of the 1886 Charleston, South Carolina earthquake based on an analysis of liquefaction hazard in the Charleston peninsula. The results show that the ground shaking level of the 1886 event may be represented with moment magnitude Mw = 6.9 and peak ground surface acceleration amax = 0.2 g. Finally, the liquefaction hazard in the Charleston quadrangle is evaluated and mapped using the ground motion that corresponds to the 475-year return period. Details of this assessment, including limitation of the results, are presented.