Geofyzikální ústav Akademie věd ČR, v.v.i.

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Theory of seismic wave propagation in complex media

We study seismic wave propagation in 3D laterally inhomogeneous, isotropic or anisotropic, perfectly elastic or anelastic media with curved interfaces. As the basic tool for the interpretation we use high-frequency asymptotic methods such as the ray method or its various modifications and generalizations (Gaussian beam summation method, coupling ray theory, etc.).

Most of our theoretical results are published in international journals devoted to geophysics; we also develop algorithms and program packages based on our theoretical results.

At present, we are working actively on the following topics:

Weak-anisotropy approximation. Use of the perturbation theory in the equations describing wave behaviour in weakly or moderately anisotropic media, i.e., media, which differ weakly or moderately from an isotropic background.
Gaussian beam computation in inhomogeneous isotropic or anisotropic media.
Wave propagation in weakly attenuating isotropic or anisotropic media.


The methods developed are being applied to:

Weak anisotropy approximation is used in the following applications:

  • first-order P-wave ray tracing and ray-theory wavefield calculation in layered inhomogeneous weakly or moderately anisotropic media;first- and second-order S-wave coupling ray theory calculations in inhomogeneous weakly or moderately anisotropic media;
    first- and second-order expressions for the phase and ray velocity in inhomogeneous weakly or moderately anisotropic media;
  • first- and second-order moveout formulae for P and S waves in homogeneous weakly or moderately anisotropic layers;
  • VSP traveltime inversion in weakly or moderately anisotropic media;
  • local determination of anisotropy from VSP measurements of tarveltimes and polarization.


Gaussian beams are used in the computations of seismic wavefields in isotropic as well as anisotropic or weakly anisotropic media by the summation of Gaussian beams.

Weak-attenuation concept is used to calculate seismic wavefields in isotropic or anisotropic, weakly attenuating media.


Members of the team
 
Ivan Psencik
Bohuslav Ruzek
Jan Sileny
Vaclav Vavrycuk