GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 GNGTS 2023 In short, the 50-m-long trench 11 was opened across the fault scarp carved in the Patino alluvial fan (Patino synthetic splay), where we have found well stratified gravels and paleosols in the footwall vs massive debris and colluvia in the hanging wall. In the fault zone, the presence of an ancient, multi-faulted colluvial wedge, that we dated ~7.5 kyr BP, accounts for several faulting events since the Middle Holocene. The last event here has a vertical offset > 1 m, and occurred after 1395-1445 AD and before 1640-1805 AD, being surely referable to the destructive, January 14, 1703 earthquake (Mw 6.9). Figure 2. Nick’s burial next to the antithetic Norcia splay (site #2 in Fig. 1). Nick’s canines provided an AMS age of 170-10 AD that together with its fractured skull and burial location suggest that he may have died close to/because of the 99 BC earthquake. The 40-m-long trench 13 was instead opened across the antithetic Patino fault, exhuming slightly cemented fan gravels deposited in the second half of Upper Pleistocene in its footwall. These are faulted against Last Glacial Maximum gravels and an orange, Holocene paleosol. Seven AMS datings of the paleosol, of multi-faulted colluvial wedges and of other colluvial deposits allowed us to date the last event just before 1665-1820 AD, i.e., to the 1703 earthquake. A penultimate event occurred after 2360-2180 BP (age of the material forming the related colluvial wedge), overlapping the age (170-10 AD) of a buried man (our Nick) that we have discovered next to the fault (Fig. 2). The skeleton of this man was intact except for the skull that presents several fractures. Thus, we tentatively relate these indications to the effects of the known 99 BC earthquake, which falls within bots the AMS ages herein presented. At the end, a previous, not consecutive event is testified by