Reply to "Comment on 'Seismic Hazard Analysis for the U.K.: Sensitivity to Spatial Seismicity Modelling and Ground Motion Prediction Equations' by Katsuichiro Goda, Willy P. Aspinall, and Colin A. Taylor," by Roger M. W. Musson

Abstract

In Goda et al. (2013), we compared three approaches to modeling spatial seismicity properties for probabilistic seismic‐hazard assessment (PSHA) in a low‐seismicity region. The objective of our paper was to introduce seismic smoothing in the context of low‐seismicity areas, such as the United Kingdom, and to investigate the implications on expected scenario events and spectral shapes from PSHA and deaggregation for such conditions. We reported some statistical test results for seismicity rates obtained from the Cornell–McGuire source‐zone method, which were based on our construal of a published outline of the British Geological Survey (BGS) model of Musson and Sargeant (2007; hereafter: MS07). The formulation of zonal activity‐rate parameters for the BGS model in our calculations apparently contains some discrepancies from those used originally by MS071, with the consequence that, for proper comparison with the MS07 findings, our statistical test results need to be revised. The main cause of discrepancies in these tests relative to MS07 is our inclusion of more simulated events in the magnitude range M 4.0–4.5 for BGS source zones EC1, EC3H, V1H, and V4, due to the way we attempted to replicate the Gutenberg–Richter parameters summarized in MS07. Also, we had to make use of an alternative published historical catalog, with slight differences from that held by BGS; other issues are related to how historical seismicity rates from such earthquake catalogs are methodologically derived. This note amends the analysis results presented in Effects of Spatial Seismicity Modelling on Seismicity Rates section in Goda et al. (2013). In particular, results shown in figures 6a and 7b,c in …