Kriging Interpolation of Ground Motion Residuals at Liquefaction Case History Sites

Accurate estimates of ground motion intensity measures (IMs) at liquefaction case history sites are crucial as they are used on the demand side of the equation for regressing liquefaction triggering and consequence models. Therefore, it is desirable to have IM estimates that are accurate (i.e., unbiased), have defined uncertainty levels that reflect the available information, and that are consistently developed across sites in liquefaction databases. Many of the earthquakes that form the basis for current liquefaction triggering relationships occurred prior to 1999 and produced relatively limited numbers of ground motion records. By contrast, modern earthquakes in California, Japan, and elsewhere often produce large numbers of densely recorded ground motions, which enable the use of spatial interpolation to interpret shaking intensities at sites of interest. We present a method that uses Kriging to interpolate IM within-event residuals to estimate ground motions at liquefaction sites. By interpolating within-event residuals rather than IM values, the Kriging is more stable because systematic path effects and first-order site effects are accounted for.