Tomographic imaging of 3D wave-guide structures

Dobróka, M. (2005) Tomographic imaging of 3D wave-guide structures. Acta Geodaetica et Geophysica Hungarica, 40 (2). pp. 259-267. ISSN 1217-8977

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Abstract

Guided waves play important role in the investigation of near surface geological structures. As it is well-known guided waves contain information about the structural- and material parameters of the wave-guide model, so - using the methods of geophysical inversion - these characteristics can be determined by means of the frequency-dependent phase- and group velocity as well as absorption coefficient data. In this paper the approximate horizontal inversion method (Dobróka 1996) is combined with a seismic tomography procedure in order to reconstruct the 3D geometry of the wave-guide structure by means of dispersion data (group traveltimes) of the guided surface waves. The inversion procedure consists of two steps: first the local group velocities are determined at various frequencies by means of tomographic inversion of the group traveltimes, the local dispersion characteristics of the Love- or Rayleigh surface waves are then inverted in the second step. In our investigations a robust SIRT method (Dobróka 1996) is used for tomography and a simple Least Squares algorithm is applied for the inversion of the group velocity data.

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