HR: 08:45h
AN: NS11A-02    [Abstracts]
TI: Separate and Joint Inversion of TE and TM Georadar Data for Properties of Thin Surface Waveguides
AU: * van der kruk, j
EM: jvdkruk@aug.ig.erdw.ethz.ch
AF: Institute of Geophysics, Swiss Federal Institute of Technology, ETH Hoenggerberg , Zurich, 8093 Switzerland
AU: Streich, R
AF: Institute of Geophysics, Swiss Federal Institute of Technology, ETH Hoenggerberg , Zurich, 8093 Switzerland
AU: Green, A
AF: Institute of Geophysics, Swiss Federal Institute of Technology, ETH Hoenggerberg , Zurich, 8093 Switzerland
AB: Pronounced dispersion of georadar waves is observed at locations distinguished by thin surface layers of high permittivity material (e.g. water-saturated soil). The dispersion characteristics depend on the permittivity and thickness of the effective surface waveguide and the permittivity of the material below it. We introduce a scheme for estimating the values of these parameters from dispersed transverse-electric (TE) and transverse-magnetic (TM) georadar data that is analogous to recently developed methods for analysing dispersed Rayleigh waves recorded on multichannel seismic data. Our scheme involves calculating phase-velocity spectra, picking dispersion curves from the spectra, and inverting the dispersion curves for the subsurface material properties using a combined local and global minimization procedure. Application of this new scheme to synthetic and field data demonstrate its efficacy in providing the required physical property information. At locations where the surface layer is relatively distinct and uniform, inversions of the resultant high quality dispersed TE georadar data are sufficient. In more heterogeneous environments, joint inversions of the TE and TM data, which usually include information in overlapping but somewhat different frequency ranges, may be required.
DE: 0600 ELECTROMAGNETICS
DE: 0619 Electromagnetic theory
DE: 0624 Guided waves
DE: 0999 General or miscellaneous
DE: 3260 Inverse theory
SC: Near-Surface Geophysics [NS]
MN: 2005 Joint Assembly