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Bulletin de la Société Géologique de France 181, 6 (2010) 583-590
Relationships between inherited crustal structures and seismicity in the western Alps inferred from 3D structural modeling
Christian Sue 1, 2, Philippe Calcagno 3, Gabriel Courrioux 3, Pierre Tricart 4, Julien Frechet 5, François Thouvenot 6
(11/2010)

We developed a 3-D structural model of a key area in the southwestern Alps, at the boundary between the external and internal zones. Six geological bodies are analyzed: internal and external basements, Briançonnais and Piemontais zones (internal sedimentary cover nappes), exotic flyschs, and external sedimentary cover. 3D volumes of each geological body are modeled using the structural map of the area projected on the Digital Elevation Model (DEM) and 5 cross-sections. The global model is interpolated from the map, DEM, and cross sections, using the potential field method, and represented by a Voronoï diagram. The final 3D-model is used as a structural frame to plot the earthquakes of the GéoFrance3D database, allowing to precisely and quantitatively investigate the relationships between crustal structures and current seismic activity of the belt. The boundary between external and internal zones corresponds to the so-called Crustal Penninic Thrust (CPT), which is a former Oligocene major thrust. Our model establishes that this former thrust represents the western limit of the seismic activity along the Briançonnais seismic arc, currently undergoing extensional tectonics.
1 :  Domaines Océaniques
INSU – Institut d'écologie et environnement – Institut Universitaire Européen de la Mer (IUEM) – Université de Bretagne Occidentale (UBO) – Observatoire des Sciences de l'Univers – CNRS : UMR6538
2 :  UMR 6249
Univ. de Franche-Comté
3 :  Bureau de recherches géologiques et minières (BRGM)
Bureau de Recherches Géologiques et Minières (BRGM)
4 :  Laboratoire de géodynamique des chaines alpines (LGCA)
CNRS : UMR5025 – OSUG – INSU – Université de Savoie – Université Joseph Fourier - Grenoble I
5 :  Institut de physique du globe de Strasbourg (IPGS)
CNRS : UMR7516 – INSU – Université de Strasbourg
6 :  Laboratoire de géophysique interne et tectonophysique (LGIT)
CNRS : UMR5559 – Institut de recherche pour le développement [IRD] – LCPC – OSUG – INSU – Université de Savoie – Université Joseph Fourier - Grenoble I
Planète et Univers/Sciences de la Terre/Géomorphologie
Western Alps * GéoFrance3D * 3D crustal structures * Structural modeling * Active tectonics * Alpine seismicity