Tectonique et géodynamique actuelle de l'arc alpin - Approche sismotectonique et modélisation numérique

Abstract : The current tectonic regime of the western/central Alps is examined from the compilation of a synthetic database of 389 focal mechanisms. This synthesis reveals the major role of extensionnal tectonics, characterising the whole 'high' core of the belt. The directions of extension are orogen-perpendicular in these areas, while fan-shapped directions of compression are found in external domains, in a general transcurrent mode of deformation (shifted locally to extension or compression).
A model of gravitationnal re-equilibration is advanced and tested with finite element numerical modellings, firstly in 2.5D and secondly in 2D (ECORS profile). These modelling studies reveal the major role of gravitationnal body forces, producing a tectonic regime close to the one analysed in our seismotectonic analysis and interpreted as a current post-collisionnal setting in the western/central alpine belt.
Quantifications of deformation show slow deformations, of the order of 1-3 mm/y from GPS studies and 0.1-0.4 mm/y from seismological studies (the difference asking the problem of aseismic deformation in the belt). Rotation quantifications show slow rotations, of the order of 2-2.5 degres/My, probably associated with anticlockwise Apulian rotation, inducing anticlockwise rotations of the core of the alpine arc and clockwise rotations along the dextral transcurrent system of the western border of the belt.
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Submitted on : Tuesday, March 15, 2005 - 11:48:39 AM
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  • HAL Id : tel-00008598, version 1

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Bastien Delacou. Tectonique et géodynamique actuelle de l'arc alpin - Approche sismotectonique et modélisation numérique. Géologie appliquée. Université Nice Sophia Antipolis, 2004. Français. ⟨tel-00008598⟩

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