Stochastic simulation of regionalized ground motions using wavelet packets and cokriging analysis

Performance-based earthquake engineering often requires ground-motion time-history analyses to be performed, but very often, ground motions are not recorded at the location being analyzed. The present study is among the first attempt to stochastically simulate spatially distributed ground motions over a region using wavelet packets and cokriging analysis. First, we characterize the time and frequency properties of ground motions using the wavelet packet analysis. The spatial cross-correlations of wavelet packet parameters are determined through geostatistical analysis of regionalized ground-motion data from the Northridge and Chi-Chi earthquakes. It is observed that the spatial cross-correlations of wavelet packet parameters are closely related to regional site conditions. Furthermore, using the developed spatial cross-correlation model and the cokriging technique, wavelet packet parameters at unmeasured locations can be best estimated, and regionalized ground-motion time histories can be synthesized. Case studies and blind tests using data from the Northridge and Chi-Chi earthquakes demonstrate that the simulated ground motions generally agree well with the actual recorded data. The proposed method can be used to stochastically simulate regionalized ground motions for time-history analyses of distributed infrastructure and has important applications in regional-scale hazard analysis and loss estimation. Copyright (c) 2014 John Wiley & Sons, Ltd.