GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 1.1 31 so far available only for U1, we believe units U2 and U3 may span the transition from the last glacial to the deglacial conditions. Based on trench observations, preliminary age assessment, and morpho-structural data, the PF did not cause surface ruptures since 6 ka BP and probably since the Latest Pleistocene. Structural data indicate that the PF lies in the back-limb of a steep N-verging Pliocene fold- thrust train, which about 2 km north of the PF, carries the Lagonegro rocks above Middle Pliocene clay and silt of the Ofanto basin along the E-W striking Ofanto thrust fault. Because the extension axis on the PF is sub-parallel to the Pliocene shortening axis, we regard the PF as a back-limb collapse structure developed during or after thrusting, suggesting that the PF may have an early Quaternary age at most. Structural reconstructions indicate that the fault merge with the Ofanto thrust ramp at ~2 km depth where it reaches the ~4 km depth of the base of the Lagonegro basinal rocks (Nicolai and Gambini, 2007) but not the 10-12 km nucleation depth of large earthquakes in the area. References Amato A. and Selvaggi G.; 1993: Aftershock location and P-velocity structure in the epicentral region of the 1980 Irpinia earthquake . Ann. Geofis., 36 , 3-15. Amoruso A., Crescentini L. and Scarpa R.; 2005: Faulting geometry for the complex 1980 Campania-Lucania earthquake from levelling data . Geophys. J. Int., 162 , 156–168. Bello S., de Nardis R., Scarpa R., Brozzetti F., Cirillo D., Ferrarini F., di Lieto B., Arrowsmith R.J. and Lavecchia G.; 2021: Fault Pattern and Seismotectonic Style of the Campania – Lucania 1980 Earthquake (Mw 6.9, Southern Italy): New Multidisciplinary Constraints . Front. Earth Sci. 8:608063. Bernard P. and Zollo A.; 1989: The Irpinia Italy 1980 earthquake: detailed analysis of a complex normal fault . J. Geophys. Res., 94 , 1631-1648. Blumetti A.M., Esposito E., Ferreli L., Michetti A.M., Porfido S., Serva L. and Vittori E.; 2002: New data and the reinterpretation of the november 23, 1980, M 6.9, Irpinia-Lucania earthquake (Southern Apennine) coseismic surface effects . Studi Geologici Camerti, 2 , 19–27. Nicolai, C. and Gambini, R.; 2007: Structural architecture of the Adria platform-and-basin system , Boll. Soc. Geol. Ital., 7 , 21-37. Pantosti D. and Valensise G.; 1990: Faulting mechanism and complexity of the 23 November, 1980, Campania-Lucania earthquake inferred form surface observations . J. Geophys. Res., 95 , B10, 15319-15341. Pingue F. and De Natale G; 1993: Fault mechanism of the 40 seconds subevent of the 1980 Irpinia (Southern Italy) earthquake from levelling data . Geophys. Res. Lett., 20 , 911–914.