GNGTS 2013 - Atti del 32° Convegno Nazionale

Area seismotectonics. Concerning seismotectonics, the Sampeyre area is located in the inner part of the Dora Maira crystalline massif, which corresponds to the northern Tethyan margin (part of the stretched European continental crust) exhumed during the collision of the Eurasia and Africa plates. The Dora-Maira massif is a large tectonic window that crops out as a broad half-dome. On the eastern side, it is delimited by steep faults and it is directly onlapped by Tertiary deposits of the Po basin (Wheeler, 1991; Michard et al. , 1993; Avigad et al. , 2003). On the western side, it structurally underlies the oceanic Penninic nappes, under which it subducted during the early Alpine events (Eoalpine stage). The Dora Maira massif is located near the border between the internal (Penninic zone, nearly corresponding with the axial sector of the Alpine chain) and external (eastern sector at the Po Plain border) sectors of the Western Alps where the tectonic regime changes from (prevalent) extension to compression. Fig. 2 – Top panels: seismicity distribution (left panel) and seismic cross-section (right panel) after double- difference location. Bottom panels: seismic families identified by EQUI (left panel) and FIVI (right panel) stations, respectively. 19 GNGTS 2013 S essione 1.1