Multihazard Scenarios for Regional Seismic Risk Assessment of Spatially Distributed Infrastructure

Abstract

This paper introduces the multihazard optimization-based probabilistic scenario (multihazard OPS) method to create an ensemble of multihazard scenarios that can be used for efficient evaluation of spatially distributed infrastructure. Each multihazard scenario is a map depicting a possible realization of the co-occurring multiple hazard effects associated with a single earthquake, including ground motion intensity contours, liquefaction potential contours, and locations of surface fault rupture. Together, when the small set of multihazard scenarios are combined with their computed weights, they represent the probabilistic hazard in a way that captures spatial correlation, includes multiple hazards, and is computationally efficient. In demonstrating the method for Los Angeles, California, we find a set of 350 multihazard scenarios matches the regional hazard and damage with errors small enough for most practical purposes. Further reduction is possible depending on the desired tradeoff between acceptable errors and computational efficiency. A sensitivity analysis suggests it is important to consider each hazard type in determining the multihazard scenarios, although the outcome is not sensitive to the precision of the weights.