Surface faulting in Norcia (central Italy): a “paleoseismological perspective”

We carried out paleoseismological analyses in Norcia, one of the oldest town of central Italy. Four trenches were dug in late Pleistocene-Holocene deposits, across an unmapped, antithetic splay of the Norcia Fault System. The investigated fault runs through the recent settlement of the town, brushing against the middle-age city walls. We found evidence of repeated surface ruptures in the past 20 ky, the last one dated to a period fitting with the 1703 AD, catastrophic earthquake (M = 6.8). Our data (i) show definitively the late Pleistocene-Holocene activity of the Norcia Fault System, (ii) strengthen the historical accounts describing surface ruptures during the 1703 event in Norcia, (iii) cast light on the seismogenic behavior of the 70-km-long fault system between L'Aquila and Norcia (central Italy) and (iv) predict the occurrence of normal surface faulting inside the municipality of Norcia during future M ≥ 6 earthquakes.