A Stochastic Ground‐Motion Model for Switzerland

Abstract

Abstract We present a stochastic ground‐motion model for Switzerland. A model for the far‐field Fourier amplitude spectra of earthquakes is first proposed, constrained by ground motions observed from small local and regional earthquakes in addition to macroseismic intensities observed from large damaging events in Switzerland. We then use this model in a stochastic simulation technique to generate predictions of peak ground acceleration and velocity and 5%‐damped response pseudo‐spectral acceleration. We facilitate the prediction of ground motions from finite‐fault sources through the use of the R EFF distance metric and show that magnitude and distance scaling‐behavior of events up to M w 7.5 is broadly consistent with Next Generation Attenuation and Japanese models. Ground‐motion prediction uncertainty is described in terms of between‐ and within‐event uncertainties through residual analysis of response spectra. Finally, single‐station sigma is derived, accounting for the prediction uncertainty at a given site without the ergodic assumption. Consistency of the model is emphasized through its compatibility with other seismic hazard products: the model is referenced to a generic rock profile that was developed by utilizing velocity profiles of the sites of seismic stations and is calibrated at higher magnitudes to the Swiss regional macroseismic intensity prediction model. Furthermore, the model is based on moment magnitudes from the recently developed Earthquake Catalogue of Switzerland 2009 (ECOS09). The well‐defined reference for the model means that it can easily be adapted for a site‐specific application, for instance, through the use of proxies such as quarter‐wavelength velocity and travel‐time average shear‐wave velocity in the upper 30 m ( V S 30 ).