LAUSR

Using non-ergodic ground-motion models (GMMs) in probabilistic seismic hazard analysis (PSHA) for areal sources can lead to large increases in calculation time compared to PSHA based on ergodic GMMs due to the large number of branches on the logic tree required to capture the spatial correlation of the non-ergodic terms. To reduce the computation time, a Polynomial Chaos (PC) expansion with a Taylor series approximation to capture the effects of the spatial correlation effects of the non-ergodic terms is used for the hazard calculations. With these approximate analytical methods, the calculation time for a logic tree with 100 branches for the non-ergodic terms can be reduced by a factor of 50 to 100. Using the proposed analytical approximations, the loss of accuracy of the mean hazard and the epistemic fractiles of the hazard is about 2%.