Integrated geological and geophysical investigations to characterize the anthropic layer of the Palatine hill and Roman Forum (Rome, Italy)

The anthropic layer of Palatine hill (Rome, Italy) and surrounding areas was modeled with the aim of providing a valuable input for assessing local seismic hazard; results are presented in this paper. More than 200 boreholes, twenty-four Electrical Resistivity Tomography (ERT), and several Ground Penetrating Radar (GPR) surveys were integrated in order to (i) characterize the archaeological layer susceptible to seismic amplification, and (ii) map the basal surface of the anthropic cover. In terms of composition, the anthropic layer was distinguished in zones with dominant masonry remains, and zones with dominant infill. Zones with dominant masonry consist predominantly of building remains, typically alternate with sandy-pebbly fill materials with a silty-clay or pozzolan matrix. Zones with dominant infill are generally subordinate and consist of sandy-pebbles with a silty-clay or pozzolan matrix. The morphology buried below the anthropic layer was reconstructed through the integration of ERT and GPR surveys, that were calibrated and constrained using geological cross-sections, borehole and archaeological stratigraphies. The basal surface of the anthropic layer was interpolated by means of multicollocated cokriging, using buried escarpments as break lines. Thickness of the anthropic layer was than calculated starting from DTM and basal surface of the anthropic layer. Finally, the possible conditioning of the anthropic layer on local seismic amplification was discussed.