Closure to 'Epistemic Uncertainty in Site Response as Derived from One-Dimensional Ground Response Analyses' by Jonathan P. Stewart and Kioumars Afshari

摘要

We appreciate the discusser's interest in this topic and welcome the opportunity to respond to the points raised. We agree that in the context of analyzing vertical arrays, the site-to-site variability at the downhole level is combined with the site amplification variability to produce the total site-to-site variability at the ground surface. Accordingly, we have no quarrel with this argument nor with the results presented in the discusser's Fig. 1. In the following, we describe our intention with the figure in question (Fig. 10 of the original paper), comment on site-to-site variability for reference site ground motions, and comment on the utilization of ground response analyses for predicting site response. Fig. 10 was not intended to provide an apples-to-apples comparison of dispersions. This is in part for the reason mentioned by the discusser, but also because the data sets are different; much larger inventories of sites and ground motion data were used to derive the ergodic model uncertainties (Al Atik 2015; Rodriguez-Marek et al. 2013) than the ground response uncertainty (present study).