Seismic characterization of the accelerometric stations along an array in the Sulmona basin

The paper summarizes the preliminary results of 1D and 2D seismic site response analyses addressed to the seismic characterization of four accelerometric stations of the RAN (Italian Accelerometric Network) located along an array in the Sulmona alluvial basin, Abruzzo (Italy). The main uncertainties about the morphological and geotechnical soil model of the array concern the morphology and depth of the bedrock and the value of shear wave velocity, VS, at depths greater than 30m. To overcome these difficulties the available geological survey, boreholes, and field geophysical tests, including HVSR and SSR measurements from noise and aftershocks, one cross hole (CH) and two down hole (DH) tests were collected and integrated. The results of the elastic site response analyses at the RAN stations were compared with two recorded events of the Central Italy seismic sequence (24.8.2016 Mw= 6.0 and 30.10.2016 Mw=6.5 earthquakes) in terms of response spectra, amplification factors of peak ground acceleration and spectral intensity. The results revealed that the response towards the middle of the basin is about one-dimensional, while the response at the two stations closer to the border of the valley is significantly affected by the buried morphology of the tectonic contact between the sedimentary soils and the fault rock slope.