GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.2 GNGTS 2024 Comparing various seismic equipment for H/V and dispersion measurements in three sites near Ferrara (Po Plain, Italy) G. Di Giulio 1 , L. Minarelli 1 , G. Milana 1 , M. Vassallo 1 , G. Tarabusi 1 , M. Stefani 2 1 Isttuto Nazionale di Geofsica e Vulcanologia (Rome, Italy) 2 Università degli Studi di Ferrara (Ferrara, Italy) H/V spectral ratos and surface-wave analysis are very popular techniques in the engineering- seismology community to extract near-surface propertes processing data of ambient seismic vibratons (Fot et al ., 2018). The H/V ratos provide the fundamental resonance of a site (f0), the value of which is related to both the depth of the main impedance contrast and the shear-wave velocity (Vs) of the sof deposit (Molnar et al., 2022). Surface-wave analysis is largely used for the extracton of Rayleigh and Love dispersion curves, using several sensors, deployed in mono (1D) or bi-dimensional (2D) feld geometry, for recording ambient vibratons (passive case). Surface-wave analysis computes dispersion curves for Rayleigh and Love waves (R and L, respectvely), through frequency-wavenumber (f-k) and spatal autocorrelaton (SPAC) methods (for methodology details see Hailemikael et al., 2023). Recent advances in the technology of seismic equipment make it possible to use many seismic sensors, diferent in propertes and cost, for measurements the H/V and dispersion curves. In this work, the research aim is to test the performance of diferent equipment in the estmaton of the feld curves (i.e. H/V and surface-wave dispersion). We show H/V and surface-wave curves (Rayleigh and Love), acquired with diferent sensors and feld geometry, in three case studies from the Ferrara area, Po Plain (Italy). The Po sedimentary basin is the largest of Italy and is characterized by tck, sof terrigenous deposits and low-frequency resonance (Mascandola et al ., 2021). One of the selected sites is within the Ferrara city wall, near the Jewish cemetery, one in the village of Casaglia, about 9 km north-east of the city centre, one in the Pieve di Cento municipality, 20 km south-west of Ferrara town (Fig. 1). At each of the three sites, in October 2020, the following equipment for recording ambient vibratons was used: i) twelve seismic 24-bit dataloggers (Refek 130) coupled with Lennartz three-components velocimeter (Le3D) with eigen-frequency of 0.2 Hz, ii) seven all-in-one three-components Terrabot statons produced by Sara Electronics, with an eigen-frequency of 4.5 Hz, iii) twenty-four vertcal geophones with eigen-frequency of 4.5 Hz connected to a mult-channel staton (Geode manufactured by Geometrics).