GNGTS 2014 - Atti del 33° Convegno Nazionale

tectonic evolution of the region in the past, but also to help understanding where active faults are located, and which is their seismogenic potential. Scenarios of concentration of energy of future events can thus be simulated for mitigating the seismic hazard especially in the more prone areas. Many direct and indirect data were collected in the Po Plain for hydrocarbon explorations during the past decades, reaching investigation depths often comparable with the foci of the recent earthquakes. Unfortunately, these data are often classified and thus they are hardly available for researchers. However, even when available, for example seismic reflection profiles and gravimetry, the information have insufficient resolution in order to document the most recent activity of the tectonic structures. Indeed, evidences of such activity should be searched for at shallower depths, say within the first few hundreds meters, and this represents the main target of the present reserch. With this premise and in order to contribute to this task, we planned a geophysical survey across some major tectonic structures affecting the subsoil of the eastern Po Plain. Our investigation is based on several passive seismic measurements carried out along the profiles with a mean distance of 1 km; in particular, we applied the ESAC (Aki, 1957, 1964; Asten and Henstridge, 1984; Ohori et al. , 2002) and Re.Mi. methods (Louie, 2001; Stephenson et al., 2005), which could provide information in the first 100-150 m. Accordingly, each measurement gives the vertical distribution of the shear waves velocity, i.e. 1D models, down to a depth of ca. 150 m. All vertical models have been thus interpolated to generate a pseudo-2D section. Both profiles are ca. 27 km-long and are oriented SSW-NNE, i.e. almost perpendicular to the regional trend of the buried tectonic structures belonging to the central sector of the Ferrara Arc. The western profile runs between Cento and Bondeno, while the eastern one between Traghetto and Formignana (Fig. 1). In this paper, we describe and comment the profile west of Ferrara, while measurements for the eastern profile are still in progress. Fig. 1 – Simplified structural map of the eastern sector of the Po Plain showing the major Ferrara Arc and the two minor Adriatic and Romagna arcs. The traces of the measurement profiles (1 and 2) and of a geological section represented in Fig. 3 (C-C’) are also shown . 118 GNGTS 2014 S essione 1.2