Université de Neuchâtel

Extensional neotectonics around the bend of the Western/Central Alps: an overview

Sue, Christian ; Delacou, Bastien ; Champagnac, Institut de Géologie, Université de Neuchâtel, Switzerland ; Allanic Cecile ; Tricart, Pierre ; Burkhard, Martin

In: International Journal of Earth Sciences, 2007, vol. 96, no. 6, p. 1101-1129

The Western Alps’ active tectonics is characterized by ongoing widespread extension in the highest parts of the belt and transpressive/compressive tectonics along its borders. We examine these contrasting tectonic regimes using a multidisciplinary approach including seismotectonics, numerical modeling, GPS, morphotectonics, fieldwork, and brittle deformation analysis. Extension appears to be...

Université de Neuchâtel

Quantification of strain rate in the Western Alps using geodesy: comparisons with seismotectonics

Delacou, Bastien ; Sue, Christian ; Nocquet, Jean-Mathieu ; Champagnac, Jean-Daniel ; Allanic, Cécile ; Burkhard, Martin

In: Swiss Journal of Geosciences, 2008, vol. 101, no. 2, p. 377-385

The contrasted seismotectonic regime of the Western Alps is characterized by radial extension in the high chain, combined with local compressive areas at the foothill of the belt, and everywhere occurrence of transcurrent tectonics. Here, we compare this seismotectonic regime to a large-scale compilation of GPS measurements in the Western Alpine realm. Our analysis is based on the raw GPS...

Université de Neuchâtel

Aseismic deformation in the Alps: GPS vs. seismic strain quantification

Sue, Christian ; Delacou, Bastien ; Champagnac, Jean-Daniel ; Allanic Cecile ; Burkhard, Martin

In: Terra Nova, 2007, vol. 19, no. 3, p. 182-188

Neotectonics of the Western and Central Alps is characterized by ongoing widespread extension in the highest zones of the chain and transcurrent/compressive tectonics at the external limits of the belt. The overall geodetically measured deformations also indicate extension across the Western Alps. There is a good qualitative coherency between seismotectonic and geodetic approaches. Here we...

Université de Neuchâtel

Origin of the current stress field in the western/central Alps : role of gravitational re-equilibration constrained by numerical modeling

Delacou, Bastien ; Sue, Christian ; Champagnac, Jean-Daniel ; Burkhard, Martin

In: Deformation Mechanisms, Rheology and Tectonics : from Minerals to the Lithosphere, 2005, vol. 243, p. 295-310

We interpret the strain and stress fields of the western / central Alpine arc on the basis of 2.5D finite element modelling and a recent seismotectonic synthesis. Models have fixed boundary forces and different crustal geometries, so that they respond to buoyancy forces (variations in gravitational potential energies). The seismotectonic regime, characterized by orogen-perpendicular extension in...

Université de Neuchâtel

Brittle orogen-parallel extension in the internal zones of the Swiss Alps (South Valais)

Champagnac, Jean-Daniel ; Sue, Christian ; Delacou, Bastien ; Burkhard, Martin

In: Eclogae Geologicae Helvetiae, 2003, vol. 96, p. 1-14

The latest Alpine faulting is examined in the Valais region of the Swiss Alps. We used satellite imagery and a 25m Digital Elevation Model to identify and map geomorphic features such as fault scarps and lineaments. Verification, fault characterization and fault planes / striae measurements for paleostress analysis were conducted in the field. We identified three fault families that post-date...

Université de Neuchâtel

Active strike-slip faulting in the Chablais area (NW Alps) from earthquake focal mechanisms and relative locations

Delacou, Bastien ; Deichmann, Nicholas ; Sue, Christian ; Thouvenot, François ; Champagnac, Jean-Daniel ; Burkhard, Martin

In: Eclogae Geologicae Helvetiae, 2005, vol. 98, p. 189-199

The Chablais area is characterized by a complex geological setting, resulting from the transport of nappes of various internal origins (the Prealpine nappes), thrusted in Oligocene times onto the Helvetic cover of the external zones of the Alps. While the structural setting and timing of nappe emplacement are well understood, current tectonics and associated faulting remain unclear. The detailed...

Université de Neuchâtel

Present-day geodynamics in the bend of the western and central Alps as constrained by earthquake analysis

Delacou, Bastien ; Burkhard, Martin ; Champagnac, Jean-Daniel ; Sue, Christian

In: Geophysical Journal International, 2004, vol. 158, p. 753-774

The contrasted tectonics of the western/central Alps is examined using a synthesis of 389 reliable focal mechanisms. The present-day strain regime is mapped and interpolated for the entire Alpine belt based on a newly developed method of regionalization. The most striking feature is a continuous area of extension which closely follows the large-scale topographic crest line of the Alpine arc....