Does Long-Term GPS in the Western Alps Finally Confirm Earthquake Mechanisms?

A. Walpersdorf 1 L. Pinget 1 P. Vernant 2, 3 C. Sue 4 A. Deprez 1 Stéphane Baize 5 Pascale Bascou 1 Sandrine Baudin 3 Olivier Bock 6 Pierre Briole 7 José Cali 8 Jean-Paul Cardagliaguet 9 Cédric Champollion 3 Olivier Charade 10 Jean Chéry 3 Nathalie Cotte 1 Olivier Dauteuil 11 Eric Doerflinger 3 Thierry Duquesnoy 12 Stéphane Durand 8 Romain Fages 12 Gilbert Ferhat 13 Mireille Flouzat 14 Bruno Garayt 12 Michel Gay 15, 16 Médéric Gravelle 17 Mikaël Guichard 17 Jacques Hinderer 13 François Jouanne 1 Charly Lallemand 14 Frédéric Masson 13 Elise-Rachel Mathis 12 Stéphane Mazzotti 3 Jean-Luc Menut 18 Frédérique Moreau 11 Laurent Morel 8 Joelle Nicolas 8 Jean-Mathieu Nocquet 18 Laurent Ott 15, 16 Félix Perosanz 19 Thierry Person 12 Etienne Poirier 17 Alexis Rigo 7 Lucie Rolland 18 Alvaro Santamaria-Gomez 19 Sébastien Saur 12 Oona Scotti 5 Anne Socquet 1 Patrice Ulrich 13 Joël Van Baelen 20 Mathilde Vergnolle 18 Maurin Vidal 18 Christophe Vigny 7 Thierry Villemin 21 Guy Wöppelmann 17
Abstract : The availability of GPS survey data spanning 22 years, along with several independent velocity solutions including up to 16 years of permanent GPS data, presents a unique opportunity to search for persistent (and thus reliable) deformation patterns in the Western Alps, which in turn allow a reinterpretation of the active tectonics of this region. While GPS velocities are still too uncertain to be interpreted on an individual basis, the analysis of range-perpendicular GPS velocity profiles clearly highlights zones of extension in the center of the belt (15.3 to 3.1 nanostrain/year from north to south), with shortening in the forelands. The contrasting geodetic deformation pattern is coherent with earthquake focal mechanisms and related strain/stress patterns over the entire Western Alps. The GPS results finally provide a reliable and robust quantification of the regional strain rates. The observed vertical motions of 2.0 to 0.5 mm/year of uplift from north to south in the core of the Western Alps is interpreted to result from buoyancy forces related to postglacial rebound, erosional unloading, and/or viscosity anomalies in the crustal and lithospheric root. Spatial decorrelation between vertical and horizontal (seismicity related) deformation calls for a combination of processes to explain the complex present-day dynamics of the Western Alps.
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Article dans une revue
Tectonics, American Geophysical Union (AGU), 2018, 37 (10), pp.3721-3737. 〈10.1029/2018TC005054〉
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Soumis le : mercredi 20 février 2019 - 08:34:56
Dernière modification le : vendredi 22 février 2019 - 14:38:41

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A. Walpersdorf, L. Pinget, P. Vernant, C. Sue, A. Deprez, et al.. Does Long-Term GPS in the Western Alps Finally Confirm Earthquake Mechanisms?. Tectonics, American Geophysical Union (AGU), 2018, 37 (10), pp.3721-3737. 〈10.1029/2018TC005054〉. 〈hal-01947724〉

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