Estimating Cross-Coupling in Site Response by Seismic Noise Interferometry: an Example from an Alpine Valley (northeastern Italy)

The assessment of site response is an important task for improved seismic hazard estimation. The standard tools and approaches, however, generally neglect the cross-coupling effect among the three components of motion due to heterogeneities in the underground structure. In this study, we propose a means to estimate cross-coupling effects by the inversion of the deconvolved wavefield derived from seismic noise analysis. These functions are obtained by deconvolving the three components of the ground motion recorded at a site with those recorded at a reference site. The proposed procedure is applied to a set of recordings collected in the Sarca Valley (northeastern Italy) by a temporary seismometric network. The results show that the cross-coupling components are not negligible, and are related to lateral variations in the bedrock surface and heterogeneities within the sedimentary cover.