Integrated seismic and electrical imaging with clustering for the hydro-mechanical screening of a high-altitude earthfill dam

Earthen dams located in high mountain environments are exposed to intense environmental stresses due to strong freeze-thaw cycles that can affect material integrity. Climate change can further amplify these stresses through the increasing frequency of extreme events and natural hazards. At the same time, their remote locations and hostile environmental conditions may be challenging for monitoring instrumentation. For this reason, a preliminary and comprehensive characterization of these infrastructures is fundamental to define the best monitoring strategies. In this study, we conducted an integrated geophysical characterization of an Alpine artificial reservoir (Fourcare dam, Aosta Valley), to monitor the water infiltration processes within the dam. We combined Electrical Resistivity Tomography (ERT) and active seismic surveys, including both seismic refraction tomography and surface wave analyses, to investigate the hydrological and mechanical properties of the embankment. To integrate the parameters resulting from the two geophysical methods and identify potentially critical subsurface layers, we applied clustering of the obtained electrical resistivity data and seismic parameters (i.e. shear wave velocity and surface wave autospectral density). The joint use of ERT and seismic methods, together with the cluster analysis, provided a consistent and physically coherent framework for the identification of anomalies potentially linked to hydraulic infiltrations, supporting the non-invasive screening of this remote alpine infrastructure.