Multipath Transfer-Function Correction Method to Predict Site-Specific Amplification at City Scale

The site -specific amplification of seismic waves is an essential component of local seismic hazard assessment. It can be evaluated from empirical data, but measurements are feasible just in a limited number of locations. Hence, at the city scale, there is a need for the theoretical prediction and interpolation of the amplification. In this article, we introduce a physics -based method to predict the site -specific amplification and duration in a broad frequency range. The method is based on a novel energy -based concept of the multipath propagation of waves in viscoelastic media with random heterogeneities. The amplification is expressed by the surface -outcrop transfer function of the multipath wave propagation, which is defined by expected values of the energy spectral ratio. The method is applied to the near -surface 2D velocity model in the city of Zurich in Switzerland. The predicted amplification is validated by empirical data at a nearby seismic station, and it is compared with the soil class and other site -condition proxies. Finally, the method performance is demonstrated by the prediction of site -specific seismic waveforms and response spectra for the 2022 ML 4.7 Mulhouse earthquake.