The Earthquake Spectra Editorial Board and the EERI Board of Directors have selected the paper “Non-Ergodic Site Response in Seismic Hazard Analysis,” Earthquake Spectra, Vol. 33, No. 4, pp. 1385-1414, by Jonathan P. Stewart, Kioumars Afshari, and Christine A. Goulet, as one of two winners of the Outstanding Earthquake Spectra Paper of 2017 (Vol. 33).

The paper was recognized for addressing the complex challenges of relaxing the ergodic assumption (whereby average source, path, and site effects from large strong motion dataset are applicable to any site of interest) in order to accommodate the lower uncertainties associated with site-specific site response effect that can be characterized. Relative to ergodic assumptions, non-ergodic hazard analyses normally reduce ground motions, so their consideration is key for probabilistic seismic hazard analyses at critical sites, particularly at long return periods. Stewart et al. also presented the tools needed for computing the non-ergodic standard deviation by removing site-to-site variability, properly considering the effects of soil nonlinearity.

Both Afshari and Goulet were advised by Professor Jonathan P. Stewart, who gave the Joyner Lecture on this topic in 2016. The methodology described in the paper has been applied on several major projects, including the Lucas Museum on Narrative Art, near the USC campus (collaboration with Engeo, which is a CEE Partner firm).

UCLA Civil and Environmental Engineering

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