GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Single-staton ambient noise measurements to detect faults below the ground surface in the Fucino basin. D. Famiani 1 , F. Cara 1 , G. Di Giulio 2 , M. Vassallo 2 , G. Milana 1 1 Isttuto Nazionale di Geofsica e Vulcanologia, Rome, Italy. 2 Isttuto Nazionale di Geofsica e Vulcanologia, L’Aquila, Italy. Microzonaton studies generally focus their atenton to the characterizaton of urban areas distnguishing stable zones from those prone to seismic amplifcaton or unstable in general, including also those related to the presence of faults. In order to face this last task, the classical approach in the frst-level of microzonaton studies is based on geological evidence and informaton coming from previous studies which allows us to hypothesize the locaton of the seismic fault line. However, geological evidence or previous studies are ofen missing but there may be clues of the presence of hidden actve faults that it is important to defne for urban development or assessment. In all cases, the exact localizaton of the fault traces is preliminary to perform refecton profles and seismic trenches to establish whether the faults are actve or not. In this study, we propose and illustrate a procedure that we applied in the Fucino basin (Central Italy) and that has been published in Famiani et al. (2022). The procedure is based on single-staton microtremor recordings. In partcular, in Famiani et al. (2022) we performed 88 single-staton ambient noise measurements (Fig. 1) and used the horizontal-to-vertcal spectral rato (HVNSR) technique to investgate hidden faults in the Trasacco municipality located in the southern part of the Fucino basin, where microzonaton studies pointed out hypothetcal fault lines crossing the urban area with the Apennine orientaton. The noise survey consisted of two steps: frst, the measurement points were set in a regular grid geometry; second, we individuated areas where increasing the spatal density of measurements.