Shear-Wave Splitting in the Alpine Region

Gerrit Hein, Petr Kolinsky, Irene Bianchi, Götz Bokelmann

Publications: Contribution to journalArticlePeer Reviewed

Abstract

To constrain seismic anisotropy under and around the Alps in Europe, we study SKS shear wave splitting from the region densely covered by the AlpArray seismic network. We apply a technique based on measuring the splitting intensity, constraining well both the fast orientation and the splitting delay. Four years of teleseismic earthquake data were processed, from 723 temporary and permanent broad-band stations of the AlpArray deployment including ocean-bottom seismometers, providing a spatial coverage that is unprecedented. The technique is applied automatically (without human intervention), and it thus provides a reproducible image of anisotropic structure in and around the Alpine region. As in earlier studies, we observe a coherent rotation of fast axes in the western part of the Alpine chain, and a region of homogeneous fast orientation in the Central Alps. The spatial variation of splitting delay times is particularly interesting though. On one hand, there is a clear positive correlation with Alpine topography, suggesting that part of the seismic anisotropy (deformation) is caused by the Alpine orogeny. On the other hand, anisotropic strength around the mountain chain shows a distinct contrast between the Western and Eastern Alps. This difference is best explained by the more active mantle flow around the Western Alps. The new observational constraints, especially the splitting delay, provide new information on Alpine geodynamics.

Original languageEnglish
Pages (from-to)1996–2015
Number of pages20
JournalGeophysical Journal International
Volume227
Issue number3
DOIs
Publication statusPublished - Dec 2021

Austrian Fields of Science 2012

  • 105122 Seismic

Keywords

  • ASTHENOSPHERIC FLOW
  • Body waves
  • CONSTRAINTS
  • Dynamics of lithosphere and mantle
  • EASTERN ALPS
  • EVOLUTION
  • Europe
  • MANTLE DEFORMATION
  • SEISMIC ANISOTROPY BENEATH
  • SLAB
  • SUBDUCTION
  • Seismic anisotropy
  • TETHYS
  • TOMOGRAPHY

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