Seismic Hazard and Loss Analysis for Spatially Distributed Infrastructure in Christchurch, New Zealand

The new Extended Optimization-Based Probabilistic Scenario method produces a small set of probabilistic ground motion maps to represent the seismic hazard for analysis of spatially distributed infrastructure. We applied the method to Christchurch, New Zealand, including a sensitivity analysis of key user-specified parameters. A set of just 124 ground motion maps were able to match the hazard curves based on a million-year Monte Carlo simulation with no error at the four selected return periods, mean spatial correlation errors of 0.03, and average error in the residential loss exceedance curves of 2.1%. This enormous computational savings in the hazard has substantial implications for regional-scale, policy decisions affecting lifelines or building inventories since it can allow many more downstream analyses and/or doing them using more sophisticated, computationally intensive methods. The method is robust, offering many equally good solutions and it can be solved using free open source optimization solvers.