Estimation of spectral amplification coefficients of seismic motion in Greece and comparison with the corresponding coefficients of  the “Eurocode 8”.

In this study the critical role of spectral amplification factors (SAFs) in seismic hazard estimation is emphasized with respect to Seismic Regulations such as Eurocode 8. Thorough analysis is carried out of accelerogram recordings at six (6) selected  stations in Greece, identified as reference sites on “rock” formations. The primary focus is in developing Vsz profile models down to the seismological(H3000) and engineering bedrock (H800), based on single station ambient noise H/V spectral ratio and on the Diffuse Field Concept, by employing the respective “HV-inv” software tool (Garcia-Jerez et al. 2016). These profiles are compared with Vsz ones at the same sites as obtained by ambient noise array data using the Geopsy software tool. Furthermore, all spectra from the data recorded at of the aforementioned reference stations have been corrected for the horizontal and vertical site amplification, among others due to shallow weathered layers, by considering as engineering bedrock the H800 soil-rock interface. After thecorrection of spectra, a parametric Generalized Inversion Technique (GIT) is applied, to theoretically estimate properties of the factors influencing seismic-wave propagation (i.e.  source, path, and site factors). The site spectral amplification factors (SAFs) as estimated by GIT for more than 150 accelerometer stations in Greece, are grouped in site categories according to Eurocode 8. The SAFs estimated in this study, are compared with those proposed in Eurocode 8 and the results are presented and discussed in light of seismic hazard assessment in Greece.