Influence of source-to-site distance and diagenesis on liquefaction triggering of 200,000-year-old beach sand

Abstract

Liquefaction triggering of the outcropping 200,000-year-old Ten Mile Hill beds sand facies (Qts) near Charleston, South Carolina is characterized in this paper. The characterization includes evaluating the relative susceptibility to liquefaction of Qts assuming a uniform seismic load and using seismic cone penetration testing at 46 sites, the ratio of measured small-strain shear wave velocity to estimated small-strain shear wave velocity (MEVR), and the liquefaction potential index (LPI). The computed LPI values indicate a slight decrease in the liquefaction susceptibility of Qts moving away (5 to 30 km) from the likely source of the 1886 Charleston earthquake (Mw ~ 7). Also characterized is the liquefaction potential of Qts during the Charleston earthquake and a range of other earthquake loadings. The results for the range of other earthquake loadings are summarized in terms of liquefaction probability curves, which provide a method for mapping liquefaction potential in Qts. A back-calculated, lower-bound diagenesis correction factor of 1.11 for areas of Qts where liquefaction surface manifestations were not observed agrees well with the published data.