Geotechnical characterization of a slope subsoil for seismic risk assessment purposes: the Chieuti case study.

One of the key points in the seismic risk assessment is the accurate prediction of the seismic shaking at ground surface, which is strongly affected by local site conditions including the uneven topography, the subsoil stratigraphy and the buried morphologies. The analysis of the local seismic response, usually performed through numerical simulations, is strongly dependent on the assumed geotechnical subsoil model, defined through site investigations and laboratory tests. The paper presents the geotechnical seismic characterization of the subsoil deposit of a landslide-prone natural slope, located in Chieuti, a little town in the north of Apulia (Southern Italy). The western slope of Chieuti is currently location of a deep, slow-moving paleo-landslide interacting with the urban area. The occurrence of a low-intensity earthquake in August 2018 induced an aggravation of the already diffuse landslide-related damage to the buildings and infrastructure at the crest of the slope. This prompted the execution of a detailed geotechnical and geophysical campaign, including boreholes, down-hole, seismic surface waves and resonant column tests to characterize the dynamic behaviour of slope soil for seismic risk assessment purposes. The paper discusses the integration and interpretation of the site and laboratory investigation data for the definition of the geotechnical subsoil model to be implemented in the numerical simulations of the local seismic response of the slope.