GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 1.1 109 basin, while other authors supposed the presence of oblique faults bounding the basin to the south (Coltorti and Farabollini, 1995). For this reason, some authors (e.g., Cheloni et al. , 2017; Chiaraluce et al., 2017; Scognamiglio et al., 2018) suggested that the assumption that only a single planar fault slipped in the 30 October earthquake may not be exhaustive. In this context, we revisited the 30 October 2016 Mw 6.6 Mt. Vettore-Mt. Bove earthquake, which represents the largest normal faulting seismic event in Italy and worldwide, observed with an unprecedented set of modern geophysical techniques. In particular, we present new geodetic modelling from the sequence integrating it with the coseismic evidence of surface faulting, aftershocks distribution and long-term geological data to mitigate the problems of non-uniqueness associated with the individual datasets. In particular, we reinvert the already published geodetic data that is, GPS and InSAR observations, integrating them with the static offsets derived from a local near-field GPS network and with the displacements derived from strong-motion data. We explored the structures involved in the coseismic dislocations and we discussed on the feasibility of a simple “conceptual” half-graben dislocation model versus the implication of a more complex fault array, i.e., invoking the primary simultaneous multi-fault rupture of both normal fault systems and cross-structure, in reconciling the earthquake dislocation. Our results revealed that the 2016 Central Italy earthquake sequence on the Mt.Vettore-Mt. Bove fault system is the result of the activation of a half-graben normal fault system, that simultaneously ruptured both the master SW-dipping normal fault and a number of synthetic and antithetic faults, whose presence is testified by Quaternary geological observations, geodetic and seismological evidence and along which surface faulting took place. References Civico R., Pucci S., Villani F., Pizzimenti L., De Martini P.M., Nappi R. and the Open EMERGEO Working Group; 2018: Surface ruptures following the 30 October 2016 Mw 6.5 Norcia earthquake, central Italy . Journal of Maps, doi:10.1080/17445647.2018.1441756. Cheloni D., De Novellis V., Albano M., Antonioli A., Anzidei M., Atzori S., Avallone A., Bignami C., et al.; 2017: Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data . Geophys. Res. Lett., 44 (13), 6778-6787, doi:10.1002/2017GL073580. Chiaraluce L., Di Stefano R., Tinti E., Scognamiglio L., Michele M., Casarotti E., Cattaneo M., De Gori P., et al.; 2017: The 2016 Central Italy seismic sequence: A first look at the mainshocks, aftershocks and source models. Seismol. Res. Lett., 88 (3), doi:10.1785/0220160221. Coltorti M. and Farabolini P.; 1995: Quaternary evolution of the Castelluccio di Norcia basin (Umbro-Marchean Apennines, central Italy). Quaternario, 8 (1), 149-166. Pierantoni P., Deiana G. and Galdenzi S.; 2013: Stratigraphic and structural features of the Sibillini Mountains (Umbria-Marche Apennines, Italy ). Italian Journal of Geosceinces, 132 (3), 497-520. Pizzi A. and Galadini F.; 2009: Pre-existing cross-structures and active fault segmentation in the northern-central Apennines (Italy). Tectonophysics, 476 (1-2), doi:10.1016/j.tecto.2009.03.018. Scognamiglio L., Tinti E., Casarotti E., Pucci S., Villani F., Cocco M., Magnoni F., Michelini A. and Dreger D.; 2018: Complex fault geometry and rupture dynamics of the Mw 6.5, 2016, October 30 central Italy earthquake. J. Geophys. Res., 123 (4), doi:10.1002/2018JB015603.