Liquefaction Response of Soils in Mid-America Evaluated by Seismic Cone Tests

The Mid-America earthquake region is recognized as containing significant seismic hazards from historically-large events that were centered near New Madrid, MO in 1811 and 1812 and Charleston, SC in 1886. Methods for evaluating ground hazards as a result of soil liquefaction and site amplification are needed in order to properly assess risks and consequences of the next seismic event in these areas. In-situ tests provide quick, economical, and practical means for these purposes. For this research effort, seismic piezocone penetration tests (SCPTu) have been performed at a number of sites in the heart of the Mid-America earthquake regions. Many of these sites have already been associated with liquefaction features such as sand dikes, sand boils, or subsidence, observed during geologic and paleoseismic studies. Data collected at these sites have been analyzed under current methodologies to assess the validity and internal consistency of empirical relations developed for Chinese, Japanese, and Californian interplate earthquakes when applied to historical Mid-American earthquakes. Validation of extrapolation of cyclic resistance curves to high cyclic stress ratio values will be considered. Lower bound estimates of moment magnitude (M_w) from parametric studies on SCPTu data indicate an earthquake event of magnitude greater than 7.0 would have been necessary to induce soil liquefaction at the sites studied.