GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 windows; a detrend and a 5% cosine taper were applied to each window, and the spectra were smoothed by using a triangular moving window with a frequency-dependent half-width (10% of central frequency). The horizontal components were combined with the geometric average. Three measurements were performed at each site and the best quality one was chosen following the criteria proposed by Albarello et al. (2011). Theoretical HVSR curves were simulated considering the models mentioned above and taking into account the Vs and Vp profiles of the considered down-holes; density values were deduced from Vp values following the relationships proposed by Brocher (2005) and, for not purely elastic models, damping values for Vp and Vs are assumed equal to 0.01 for all the layers. Finally, these curves were compared with the respective experimental ones in order to evaluate the differences in terms of frequency and peak amplitude as well as of overall trend. References Albarello, D.; Cesi, C.; Eulilli, V.; Guerrini, F.; Lunedei, E.; Paolucci, E.; Pileggi, D.; Puzzilli, L.M.; 2011: The contribution of the ambient vibration prospecting in seismic microzoning: An example from the area damaged by the 26th April 2009 l’Aquila (Italy) earthquake. Boll. Geofis. Teor. Appl., 52, 513–538. Brocher TM.; 2005: Empirical Relations between Elastic Wavespeeds and Density in the Earth’s Crust. Bulletin of the Seismological Society of America;95:2081–92. https://doi.org/10.1785/0120050077. García-Jerez A, Piña-Flores J, Sánchez-Sesma FJ, Luzón F, Perton M.; 2016: A computer code for forward calculation and inversion of the H/V spectral ratio under the diffuse field assumption. Computers & Geosciences; 97, 67–78. https://doi.org/10.1016/j.cageo.2016.06.016. Herak M.; 2008: ModelHVSR—A Matlab® tool to model horizontal-to-vertical spectral ratio of ambient noise. Computers & Geosciences;34, 1514–26. https://doi.org/10.1016/j.cageo.2007.07.009. Lunedei E, Albarello D.; 2009: On the seismic noise wavefield in a weakly dissipative layered Earth. Geophys. J. Int. (2009) 177, 1001–1014, doi: 10.1111/j.1365-246X.2008.04062.x. Lunedei E, Albarello D.; 2016: Power spectral density function and spatial autocorrelation of the ambient vibration full-wavefield generated by a distribution of spatially correlated surface sources. Geophys J Int; 204:1817–37, https://doi.org/ 10.1093/gji/ggv559. Lunedei E, Tanzini A., Paolucci E., Albarello D.; 2022: Sui simulatori delle curve HVSR. Gruppo Nazionale di Geofisica della Terra Solida, Atti del 40°Convegno nazionale, Trieste – sessione 2.2. Nakamura Y. (1989). A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. QR Railway Technical Research Institute, 30, 25 - 33.