Single-Path Sigma and Spatial Correlation of Gmpe Residuals Deduced from a Huge Dataset in Taiwan

Abstract:

A strong ground-motion attenuation equation is an essential part in the probability seismic hazard analysis. Therefore, we need to study the strong ground-motion attenuation relationship for earthquakes in Taiwan. In this study, well processed strong ground-motion data from aiwan Strong Motion Instrumentation Program (TSMIP) in Taiwan are used to establish attenuation equations. A total of 158 earthquakes with 18,859 records are selected and nonlinear mixed-effect model with maximum likelihood method is used to accomplish the regression analysis of ground-motion attenuation relationships for peak ground acceleration (PGA), with considering earthquake source, distance, site condition (Vs30), fault mechanism, and tectonic regine. The very much concerned ground-motion variability in PSHA is reviewed and studied with huge amount of data from Taiwan. We analyzed aleatory variability firstly by direct observation on inter-event variability and site-specific variability, and then by two additional simple approaches, the variogram and the standard deviation distribution in single site stady and in single earthquake study and got spatial distribution of single-path sigma as well as their earthquake component and site component. The single-path sigma is ranging from 0.219 to 0.254. These are 58% to 64% smaller than the total sigma (0.601). If we only use aleatory variability in PSHA, then the resultant hazard level would be 20% lower than the traditional one in 2,475 year return-perid.