Ground Motion Model for Hard-Rock Sites by Surface Recordings Correction: Site-Response Estimation and GMPE Derivation

Session: Near-Surface Effects: Advances in Site Response Estimation and Its Applications
Type: Oral
Date: 4/28/2020
Time: 05:15 PM
Room: 110 + 140
Description: 

Site-specific seismic hazard assessment involves the prior knowledge of 1) the input ground-motion at a local bedrock and 2) the site-response characteristics. The definition of hard-rock motion representing a reference motion constitutes an essential need in seismic risk analyses. Empirical ground motion prediction equations (GMPEs) are currently used to predict the expected ground motion level in which V_S30 (time-averaged shear-wave velocity in the first 30 m depths) is the key parameter to account for site conditions. As GMPEs are poorly constrained for high values of V_S30, the present work develops a new ground motion prediction approach that is valid for very hard-rock sites (V_S30>1500m/s) on KiK-net network sites.

Using available velocity profiles we compute theoretical site-responses by 1D-SH simulations. These are compared to empirical site responses obtained by Standard Spectral Ratio (SSR) and Generalized Inversion Techniques (GIT). The correlation between theoretical and empirical transfer functions allows us to identify sites with a 1D-behaviour.

Surface recordings are corrected from their site response by deconvolution of the estimated transfer functions. Note that GIT allows us to obtain empirical transfer functions also for sites exhibiting 2D or 3D behaviors. Using corrected ground-motions we finally determine a set of GMPEs referred to hard-rock using (1) only records from 1D-sites and (2) records from all sites at which site-response estimate was possible. The results are compared to existing GMPEs for hard-rock sites.

Presenting Author: Hussein Shible

Authors