Statistical and spatial variability of liquefaction potential in regional mapping using CPT, SPT and V(s) data from the Oakland and Monterey Bay areas, California

Cone penetration test (CPT), standard penetration test (SPT), and shear wave velocity (Vs) are widely used for site specific evaluation of liquefaction potential and are getting increased use in regional mapping. We compare the statistical and spatial variability of SPT, CPT and V s liquefaction potential characterizations in the Oakland and Monterey Bay areas in California and use geostatistics to interpolate liquefaction potential at the site and regional scales. For the Monterey Bay area, we estimate the predictive capability of liquefaction potential measurements by comparing the predictions to observed liquefaction surface effects. We find that Vs defines large geologic units with high potential for liquefaction, while CPT characterizes small-scale variability. Overall, the liquefaction potential measurements have broad distributions and liquefaction hazard maps should provide a distribution to represent the variability. Or, alternatively, geostatistical methods can be used to interpolate between observation locations to provide a detailed map of liquefaction potential