Does Long-Term GPS in the Western Alps Finally Confirm Earthquake Mechanisms? - Archive ouverte HAL Access content directly
Journal Articles Tectonics Year : 2018

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

A. Walpersdorf
  • Function : Correspondent author
A. Deprez
Olivier Bock
Pierre Briole
José Cali
Cedric Champollion
Olivier Charade
Olivier Dauteuil
Michel Gay
Jean-Luc Menut
Jean-Mathieu Nocquet
Laurent Ott
  • Function : Author
  • PersonId : 1318081
  • IdHAL : laurentott
Félix Perosanz
Alexis Rigo
Lucie Rolland
Anne Socquet
Joël van Baelen
Mathilde Vergnolle
Maurin Vidal
  • Function : Author
Guy Wöppelmann

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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Tectonics
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hal-01947724 , version 1 (20-02-2019)

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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, 2018, 37 (10), pp.3721-3737. ⟨10.1029/2018TC005054⟩. ⟨hal-01947724⟩
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