The Late Pleistocene and Anthropocene neotectonic evidence of the La Sassa cave (Volsci Range, Italy).

We present the outcomes of a novel investigation method comprehensive of geomatic, structural geology, palaeontological, archaeological and radiometric data applied to solve the morphostructural evolution of a cave of the Apennines (La Sassa cave) and its surroundings (Volsci Range). Both structural and 3D survey highlighted the step-like shape of the cave due to normal fault steps that allowed the localized formation of concretions also enveloping archaeological layers. Sixteen 14C ages on fauna and human bones and thousands of archaeological finds provided chronological constraints of faulting in the Late Pleistocene and possibly also after the Middle Bronze Age. This method enabled us to recognize that the shape of the cave is associated with normal faults with similar orientation also occurring in the surroundings. In the cave, Late Pleistocene (32,930- 30,6744 calBC) hyena and bear bones, were found partially to fully embedded in concretions near the wall of a major fault marking the onset of syn-sedimentary faulting in the cave. There, syn-sedimentary pockets generated within small step-like metric-scaled basins preserving rich archaeological finds belonging to the Copper Age (CA, 3300-2000 calBC) and the Early and Middle Bronze Age (EBA-MBA, 1900-1200 calBC). Finally, Middle Bronze Age to Medieval collapse of blocks and concretions are found near fault zones. In our interpretation, the CA deposits progressively infill room floors, while the concretioned collapse covering the MBA hearth is evidence of crack-and-seal processes along a secondary fault zone of a segmented major normal fault of the Volsci Range with cumulative subsurface rupture length reaching up to 10-12 km and displacement in the order of 0.8-1 km, which could possibly be capable of generating an earthquake of magnitude Mw comprised between 5.1 and 5.8 depending on the fault segmentation. The structural evidence is relevant for understanding the speleogenesis from the Late Pleistocene and the human occupation of the cave. Overall, these results set the timing of faulting and thus represent the first neotectonic evolution ever documented in the Volsci Range. The outcome is of regional relevance as Late Pleistocene to Holocene/Anthropocene neotectonics were poorly constrained by the structural studies of the Apennine Tyrrhenian passive margin in southern Latium. As a result, the La Sassa findings provide temporal constraints to the recent regional tectonic evolution with implications for the local seismic hazard assessment.