Re-thinking site amplification in regional seismic risk assessment. Issue 1 (October 2020)

• Record Type: Journal Article
• Authors: Weatherill, Graeme; Kotha, Sreeram Reddy; Cotton, Fabrice
• Other Names: Pagani Marco guest-editor.; Silva Vitor guest-editor.; Jaiswal Kishor guest-editor.; Allen Trevor guest-editor.
• Is Part Of: Earthquake spectra. Volume 36:Issue 1(2020)Supplement
• Page Start: 274
• Page End: 297
• Publication Date: 2020-10
• Subjects: Earthquake hazard analysis -- ground motion -- seismic risk -- site effects -- regional mapping; Earthquake engineering -- Periodicals; Earthquake engineering; Periodicals; 624.1762
• DOI: 10.1177/8755293019899956
• Languages: English
• ISSNs: 8755-2930

Abstract

Probabilistic assessment of seismic hazard and risk over a geographical region presents the modeler with challenges in the characterization of the site amplification that are not present in site-specific assessment. Using site-to-site residuals from a ground motion model fit to observations from the Japanese KiK-net database, correlations between measured local amplifications and mappable proxies such as topographic slope and geology are explored. These are used subsequently to develop empirical models describing amplification as a direct function of slope, conditional upon geological period. These correlations also demonstrate the limitations of inferring 30-m shearwave velocity from slope and applying them directly into ground motion models. Instead, they illustrate the feasibility of deriving spectral acceleration amplification factors directly from sets of observed records, which are calibrated to parameters that can be mapped uniformly on a regional scale. The result is a geologically calibrated amplification model that can be incorporated into national and regional seismic hazard and risk assessment, ensuring that the corresponding total aleatory variability reflects the predictive capability of the mapped site proxy.