EGU22-7455, updated on 28 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Anisotropy of the Bohemian Massif lower crust from ANT - VTI model or additional azimuthal variations?

Jiří Kvapil1, Jaroslava Plomerová1, Hana Kampfová Exnerová1, and the AlpArray Working Group2
Jiří Kvapil et al.
  • 1Institute of Geophysics of the Czech Academy of Sciences, Prague, Czechia (
  • 2

Transversely isotropic lower crust of the Bohemian Massif (BM) has been revealed by an ambient noise tomography (ANT) of the BM (Kvapil et al., Solid Earth 2021). The significant feature of this 3D vSV model is the low velocity layer in the lower part of the crust at depth between 18-30 km and the Moho. The upper interface is characterized by a velocity drop in the 1D velocity models retrieved by the ANT. The interface is interrupted around boundaries of major tectonic units of the BM. The lower interface (Moho) exhibits a sharp velocity increase at 26-40km depths through the massif.

In this work we test whether we are able to detect azimuthal anisotropy in the lower crust, approximated up to now by anisotropic VTI model. We use Rayleigh wave dispersion curves evaluated from station pairs sampling the BM in the period range sensitive to the lower crust. First, we analyze seasonal variations of noise sources and their effect on quality and repeatability of dispersion curve measurements. Then we remove the effect of local heterogeneities by subtraction of synthetic dispersion curves calculated for the 3D vSV model along each station-pair raypath. Retrieved variations of azimuthal anisotropy are period-dependent with the fast velocity directions around NE-SW. We interpret the lower crust anisotropy layer as an imprint of the Variscan orogenic processes such as the NW-SE shortening of the crust and the late-Variscan strike-slip movements along boundaries of the crustal unit recorded in the interruptions of velocity drop interface in zones where anisotropic fabric of the lower crust was modified or erased.

How to cite: Kvapil, J., Plomerová, J., Kampfová Exnerová, H., and Working Group, T. A.: Anisotropy of the Bohemian Massif lower crust from ANT - VTI model or additional azimuthal variations?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7455,, 2022.


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