Seismic Vulnerability of the Sacramento-San Joaquin Delta Levees

As part of the Delta Risk Management Strategy (DRMS) project, the vulnerability of the Sacramento-San Joaquin Delta (the Delta) levees was assessed under various stressing events such as normal conditions, floods, and seismic events, and the effects of future climate change and subsidence. The seismic hazard of the project site was evaluated using a time-dependant probabilistic seismic hazard analysis to estimate the seismic hazard over the next 200 years. This paper discusses the methodology and results of a probabilistic seismic levee vulnerability analysis. The system of levees in the Delta was divided into a series of vulnerability classes using factors that differentiate the performance of the levees subjected to same earthquake ground shaking. The probabilistic evaluation of levee vulnerability (fragility) for a given vulnerability class is a function of random (aleatory) variables as well as epistemic uncertainties.