GNGTS 2014 - Atti del 33° Convegno Nazionale

54 GNGTS 2014 S essione 1.1 Pondrelli S., Salimbeni S., Perfetti P. and Danecek P.; 2012: Quick regional centroid mo���� ������ ��������� ��� ��� ment tensor solutions for the Emilia 2012 (northern Italy) seismic sequence. Ann. Geophys., 55 , doi:10.4401/ag-6146. Scognamiglio L., Margheriti L., Mele L., Tinti F.M., Bono A., De Gori P., Lauciani V., Lucente F.P., Mandiello A.G., Marcocci C., Mazza S., Pintore S. and Quintiliani M.; 2012: The 2012 Pianura Padana Emiliana seismic sequence: locations, moment tensors and magnitudes. Ann. Geophys., 55 , 549-559, http://dx.doi.org/10.4401/ag- 6159. Serpelloni E., Anzidei M., Baldi P., Casula G. and Galvani A.; 2006: GPS measurement of active strains across the Apennines. ���� ��������� Ann. Geophys., 49 , 319-329. Serpelloni E. et al.; 2012: GPS observations of coseismic deformation following the May 20 and 29, 2012, Emilia seismic events (northern Italy): data, analysis and preliminary models. ���� �� ��������� Ann. of Geophys., 55 , 759-766, doi:10.4401/ag-6168. Tizzani P., Castaldo R., Solaro G., Pepe S., Bonano M., Casu F., Manunta M., Manzo M., Pepe A., Samsonov S., Lanari R. and Sans���� ��� ����� osti E.; 2013: New insights into the 2012 Emilia (Italy) seismic sequence through advanced numerical modeling of ground deformation InSAR measurements. Geophys. Res. Lett., 40 , 1971-1977, doi:10.1002/grl.50290. Ventura G. and Di Giovanbattista R.; 2013: Fluid pressare, stress field and propagation style of coalescing thrusts from the analysis of the 20 May 2012 M L 5.9 Emilia earthquake (Northern Apennines, Italy). Terra Nova, 25 , 72- 78, http://dx.doi.org/10.1111/ter.12007. Interseismic coupling along the southern front of the Eastern Alps and implications for seismic hazard assessment in NE Italy D. Cheloni, N. D’Agostino, G. Selvaggi Centro Nazionale Terremoti, Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy Introduction. In this study we use continuous GPS observations to document the geodetic strain accumulation along the southern front of the Eastern Alps in NE Italy. The tectonic settings of NE Italy is dominated by the convergence between Adriatic and Eurasian plates (Fig. 1). At the present, the counter-clockwise rotation of the Adria microplate with respect to the stable Eurasia results in increasing convergence rates from W to E across the Alps, up to a rate of ~2 mm/yr in the Friuli region (D’Agostino et al. , 2008; Bechtold et al. , 2009). This motion, accommodated by continental collision in the south-eastern Alps, is partly or entirely absorbed within the south-eastern Alps, where the Adriatic lithosphere underthrusts beneath the mountain belt (TRANSALP Working Group, 2002). The convergence between Adria microplate and Eurasia has produced several destructive earthquakes in historical time. M > 6 earthquakes occurring along the front of the south-eastern Alps (Fig. 1) are associated with the thrust fault systems emerging at the surface along the front of the Alpine foothills (e.g., Burrato et al. , 2008). The largest instrumentally recorded Alpine earthquake is the 1976 Friuli earthquake sequence, main shocks M W 6.4, 5.9 and 6.0 (Pondrelli et al. , 2001). A recently revised source mechanisms of this sequence (Cheloni et al. , 2012), supports the hypothesis that the sequence ruptured a segment of the most external thrust front emerging at the base of the mountain front. As already proposed by Galadini et al. (2005), the distribution of the major historical earthquakes and of the 1976 Friuli earthquake sequence, suggests the presence of seismic gaps along the almost continuous external seismogenic thrust front of the south-eastern Alps. Local seismological and geodetic studies (Anselmi et al. , 2011; Barba et al. , 2013; D’Agostino et al. , 2005) have shown that some segments of the southern front of the eastern Alps are currently locked and accumulating therefore elastic deformation. The high population density and the highest density of industrial settlements among one of the most seismic regions of Italy, thus require a reliable assessment of the seismic hazard and a more complete understanding of the seismogenic potential of the faults along the southern front of the easternAlps. In this context, the observed geodetic strain measured across the thrust front,