GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.2 GNGTS 2024 Statstcal analysis between the experimental and theoretcal HVSR curves using diferent models. Tanzini 1 , E. Paolucci 2 , D. Albarello 1,3 1 University of Siena, Italy 2 University of Bologna, Italy 3 CNR-IGAG, Montelibret (Rome), Italy Abstract The ambient vibraton Horizontal to Vertcal Spectral Ratos (HVSR) (Nakamura, 1989) is a widely used technique to identfy the seismic resonance phenomena induced by the presence of seismic impedance contrasts at depth. Moreover, the HVSR curve can be used to constrain the shear wave velocity (Vs) profle in numerical inversion procedures: to this purpose, diferent HVSR forward modeling were developed in the last decades, which difer from each other both for the basic theoretcal assumptons related to the ambient vibraton wavefeld simulaton and for the phases of the involved seismic waves. In order to explore if signifcant diferences between these modeling exist, Paolucci et al. (2022) and Albarello et al. (2023) performed some comparisons using the results of large sets of numerical simulatons obtained by considering realistc Vs profles. These studies show that strong similarites between the resultng simulated curves exist. In view of these conclusions, in this work, a comparison of the diferent theoretcal HVSR modeling with experimental HVSR curves has been performed. HVSR measurements were carried out at test sites belonging to VEL (Valutazione Efet Locali) down-hole database of the Tuscany Region (htps://www.regione.toscana.it/-/banca-dat-vel) . Tanzini et al. (2023) described the procedure performed and informaton associated with the acquisiton of experimental data, and the analyzed sites were implemented from 50 to 116 DHs. The experimental HVSR measurement obtained was compared with the various theoretcal HVSR models used in Albarello et al. (2023). A minimum frequency threshold (MFT) was considered for each site, which corresponds to the maximum frequency that is reasonable to have with the Vs available from the DHs. The HVSR curves (experimental and theoretcal) were therefore compared and a statstcal analysis was performed, in partcular the Pearson coefcient and the Goodness-of- ft Index S (GoF) proposed by Anderson (2004) were calculated taking into account consideraton of the maximum peak of the curve in term of frequency (F d ) and amplitude (A d ). Finally, a global Similarity Index (I _Sim ) was calculated to relate Pearson's coefcient and Index S (F d and A d ) using diferent weights. I _Sim =(Pearson Coefcient*0.2)+(F d *0.5)+(A d *0.3) [1]