Recovering Shear-wave Anisotropy of the Lower Crust: The Influence of Systematic Errors on Travel-time Inversion

  • T. Bohlen
  • W. Rabbel
  • T. Weiss
  • S. Siegesmund
  • M. Pohl

Abstract

Studies of seismic anisotropy in situ can help to discriminate between different rock types for the lower crust. In this context we investigate the sensitivity of an iterative linearized 3-D travel-time inversion scheme for transversely isotropic media with respect to two types of systematic errors: wrong velocities and interface topography of the hanging wall of the lower crust. The computations simulate realistic field conditions such as found for the Variscan crust at the Urach geothermal anomaly. The study focusses on the possible information content of split SMS arrivals observed along two orthogonal expanding spread profiles. It ensues that an imperfect knowledge of the layer geometry is of minor importance compared to errors in the velocities of the hanging wall. In particular, upper crust anisotropy has to be considered carefully. Generally, the anisotropy of transversely polarized shear waves (SH waves) was recovered with higher accuracy than the anisotropy of vertically polarized shear waves (SV waves).

Key words

Travel-time inversion seismic anisotropy lower crust shear waves Urach 

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Copyright information

© Springer Basel AG 1999

Authors and Affiliations

  • T. Bohlen
    • 1
  • W. Rabbel
    • 1
  • T. Weiss
    • 2
  • S. Siegesmund
    • 2
  • M. Pohl
    • 3
  1. 1.Institute of GeosciencesKielGermany
  2. 2.Institute for Geology and Dynamics of the LithosphereGöttingenGermany
  3. 3.Geophysical InstituteKarlsruheGermany

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