GNGTS 2014 - Atti del 33° Convegno Nazionale

GNGTS 2014 S essione 1.1 53 and the Mirandola system in the southwest located in a more internal position. Furthermore, the Ferrara system is composed of an innermost segment, a middle segment and outermost segment. We use the dip of the fault segments proposed by the most recent work on accurate relocated aftershock (Govoni et al., 2014) which estimate the dip of the Mirandola and of the Ferrara thrusts to be approximately 70° and 45° respectively in the upper portion of the thrust. We have also tried dip angles inferred by moment tensor solutions (Pondrelli et al. , 2012; Scognamiglio et al. , 2012), which conversely suggested a lower dip angle for the Mirandola thrust. More complicated geometry (i.e., listric geometry) as proposed by Cesca et al. (2013) and Govoni et al. (2014), were also tested while looking at the misfit to the data. Preliminary inversion results show that the inferred spatial distribution of coseismic slip related to the May 20 event is in good agreement with previous inversions of geodetic data (e.g., Pezzo et al. , 2013), showing in the centre of the fault a main coseismic patch (maximum value around 100 cm) at a down-dip depth between 5-7 km on the NE fault (the Ferrara thrust). In addition on the eastern side a lower slip concentration (~20 cm) is located at deeper depths. As regards the May 29 event, the modelled slip distribution shows one main coseismic patch in the central part of the fault with a maximum slip of ~50 cm at ~8 km depth, well correlated to the M W 5.8 May 29 event. The inversion of post-seismic deformation, assuming that the observed post- seismic displacements are due to afterslip on the fault plane related to the May 29 mainshock, yields to a main patch of afterslip located westwards and up-dip of the main coseismic patch, suggesting that afterslip was triggered at the edges of the largest coseismic asperity. References Bignami C. et al.; 2012: Coseismic deformation pattern of the Emilia 2012 seismic sequence imaged by Radarsat-1 interferometry. ���� �� ��������� Ann. of Geophys., 55 , 789-795, doi:10.4401/ag-6157. Boccaletti M., Corti G. and Martelli L.; 2011: Recent and active tectonics of the external zone of the Northern Apennines (Italy). Int. J. Earth Sci., 100 , 1331-1348, http://dx.doi.org/10.1007/s00531-010-0545-y. Bomford G.; 1971: Geodesy. Oxford University Press, New York (731 pp.). 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Pe��� ��� ������� ������� ������� ��� ����� ��� ������ ��� ��������� ��� �������� ��� ������ ��� ���������� ��� ������� zzo G., Boncori J.P.M., Tolomei C., Salvi S., Atzori S., Antonioli A., Trasatti E., Novali F., Serpelloni E., Candela L. and Giuliani R.; 2013: Coseismic Deformation and Source Modeling of the May 2012 Emilia (Northern Italy) Earthquakes. Seism. Res. Lett., 84 , 645-655, doi:10.1785/0220120171. Pieri M. and Groppi G.; 1981: Subsurface geological structure of the Po Plain (Italy). ������� ����� ���� ������������ C.N.R., Prog. Fin. Geodinamica, Pubbl., 414 , 1-13.