Dense geophysical measurements to assess 1D Vs profile of a liquefiable site in the Po Plain (Italy)

SAN0 accelerometric station recorded the second shock of the Emilia sequence revealing strong nonlinear soil behavior in agreement with observation of liquefaction nearby. This makes SAN0 a strong candidate for validating nonlinear site response methods. Despite various geotechnical investigations conducted in the area, a significant gap remains in the comprehensive characterization of site response variability and of the shear-wave velocity (Vs) profiles at the town scale. To address this gap, an extensive seismic campaign was conducted at San Felice sul Panaro to record ambient vibration noise, 43 stations deployed across the town, especially in areas affected by liquefaction, five arrays centered on SAN0 with radii from 50 to 400 m and five MASW lines. This paper presents a comprehensive dataset from the campaign, along with a complete analysis to validate the 1D assumption and retrieve a 1D soil profile beneath the SAN0 accelerometric station that is consistent with weak motion earthquake recordings. Data were analyzed using the Horizontal-to-Vertical Spectral Ratio (mHVSR) and the Ambient Vibration Array methods (AVA). We observed day-night mHVSR variations that highlighted the influence of environmental and ambient-noise source distribution factors on the site response estimation. Earthquake HVSRs (eHVSR) were computed from the aftershocks recordings at SAN0. They were compared with noise mHVSR that confirm the day-night mHVSR variations and with 1D numerical transfer function which validate the 1D soil profile proposed. Compared to weak motion eHVSR, the one from the main shock shows a shift of the main frequency peaks.