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Geoelectrical modeling of shallow structures using parallel and perpendicular arrays
Earth, Planets and Space volume 54, pages523–533(2002)
In this article we analyze the sensitivity of a geoelectrical modeling technique to image 2D shallow structures. Firstly, we extend a previously developed 2D method based on Rayleigh-Fourier expansions, in order to allow arbitrary locations for the electrodes and also 3D earth models. This method is an alternative to finite element and finite difference techniques and is especially suitable to model multilayered structures, with smooth irregular boundaries. Then, for simple 2D models we build up two synthetic pseudosections, one for electrode deployments parallel to a profile perpendicular to the strike, and other for deployments perpendicular to it. We analyze the advantages in using both pseudosections to model these structures. We also compare geoelectric results with the corresponding audiomagnetotelluric transverse electric and transverse magnetic responses. Finally, we perform a geoelectrical survey to image a shallow buried structure and show the goodness of the model fit obtained considering both pseudosections. For the examples studied here, we conclude that considering both pseudosections leads to a more accurate description of the structures. When a 2D anomaly is present, its effect on the perpendicular component is more focused, both in width and depth, than in the parallel component. Hence the perpendicular component helps to constrain the localization of the inhomogeneity. In addition, we find similarities between the geoelectric parallel and perpendicular responses and the corresponding audiomagnetotelluric transverse magnetic and transverse electric results, respectively. When inverting audiomagnetotelluric data using 2D codes, better resolution in the electrical imaging is obtained when both modes are considered; then it is expected that 2D imaging of geoelectric data including both arrays should lead to an optimization of the inversion process. Even more, if results of these inversions could be used in correlation with AMT results, it is clear that this kind of joint inversion should contribute to remove uncertainties allowing an improvement in the description of the actual structures.
Jupp, D. L. B. and K. Vozoff, Stable iterative methods for the inversion of geophysical data, Geophys. J. Roy. Astr. Soc., 42, 957, 1975.
Loke, M. H. and R. D. Barker, Rapid least-squares inversion of apparent resistivity pseudosections by a quasi-Newton method, Geophys. Prosp., 44, 131–152, 1996a.
Loke, M. H. and R. D. Barker, Practical techniques for 3D resistivity surveys and data inversion, Geophys. Prosp., 44, 499–523, 1996b.
Monteiro Santos, F., A. Dupis, A. Andrade Afonso, and L. Mendes Victor, 1D joint inversion of AMT and resistivity data acquired over a graben, J. Appl. Geophys., 38, 115–129, 1997.
Mundry, E., Geoelectrical model calculations for two-dimensional resistivity distributions, Geophys. Prosp., 32, 124–131, 1984.
Noel, M. and B. Xu, Archaeological investigation by electrical resistivity tomography: a preliminary study, Geophys. J. Int., 107, 95–102, 1991.
Oldenburg, D. W. and Y. Li, Inversion of induced polarization data, Geophysics, 59, 1327–1341, 1994.
Oldenburg, D. W., P. R. McGillivary, and R. G. Ellis, Generalized subspace method for large scale inverse problems, Geophys. J. Int., 114, 12–20, 1993.
Osella, A. and P. Martinelli, Magnetotelluric response of anisotropic 2D structures, Geophys. J. Int., 115, 819–828, 1993.
Osella, A., A. Favetto, P. Martinelli, and D. Cernadas, Electrical imaging of an alluvial aquifer at the Antinaco-Los Colorados valley in the Sierras Pampeanas, Argentina, J. Appl. Geophys., 41(4), 359–368, 1999.
Osella, A., P. Martinelli, and D. Cernadas, 2D geoelectrical modeling using a Rayleigh-Fourier method, IEEE Trans. on Geoscience and Remote Sensing, 38(3), 1–8, 2000.
Park, S. K. and G. P. Van, Inversion of pole-pole data for 3-D resistivity structure beneath arrays of electrodes, Geophysics, 56, 951–960, 1991.
Pous, J., P. Queralt, and R. Chavez, Lateral and topographic effects in geoelectrical soundings, J. Appl. Geophys., 35, 237–248, 1996.
Queralt, P., J. Pous, and A. Marcuello, 2D resistivity modeling: An approach to array parallel to the strike direction, Geophysics, 56, 941–950, 1991.
Schulz, R. and B. Tezkan, Interpretation of resistivity measurements over two-dimensional structures, Geophys. Prosp., 36, 962–975, 1988.
Spitzer, K., 3D finite difference algorithm for DC resistivity modeling using conjugate gradient methods, Geophys. J. Int., 123, 903–914, 1995. aiVan Nostrand, R. G. and K. L. Cook, Discussion of ‘Apparent resistivity for dipping beds’, by Maeda, K. (GEO-20-01-0123-0147), Geophysics, 20, 140–143, 1955.
Zhang, J., R. L. Mackie, and T. R. Madden, 3-D resistivity forward modeling and inversion using conjugate gradients, Geophysics, 60, 1313–1325, 1995.
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Bonomo, N., Osella, A. & Martinelli, P. Geoelectrical modeling of shallow structures using parallel and perpendicular arrays. Earth Planet Sp 54, 523–533 (2002). https://doi.org/10.1186/BF03353043
- Apparent Resistivity
- Transverse Electric
- Joint Inversion
- Electrical Resistivity Tomography
- Electrical Imaging