none
10.1190/1.1444839
Society of Exploration Geophysicists
Society of Exploration Geophysicists
186
4727437
5981
2021031006471100430
10.1190
20210526T06:51:12Z
20021011T15:52:42Z
75
GEOPHYSICS
GEOPHYSICS
00168033
19422156
09
2000
65
5
Electromagnetic inversion using quasi‐linear approximation
Michael S.
Zhdanov
University of Utah, Department of Geology and Geophysics, Salt Lake City, Utah 841120111
Sheng
Fang
University of Utah, Department of Geology and Geophysics, Salt Lake City, Utah 841120111
Gábor
Hursán
University of Utah, Department of Geology and Geophysics, Salt Lake City, Utah 841120111
Three‐dimensional electromagnetic inversion continues to be a challenging problem in electrical exploration. We have recently developed a new approach to the solution of this problem based on quasi‐linear approximation of a forward modeling operator. It generates a linear equation with respect to the modified conductivity tensor, which is proportional to the reflectivity tensor and the complex anomalous conductivity. We solved this linear equation by using the regularized conjugate gradient method. After determining a modified conductivity tensor, we used the electrical reflectivity tensor to evaluate the anomalous conductivity. Thus, the developed inversion scheme reduces the original nonlinear inverse problem to a set of linear inverse problems. The developed algorithm has been realized in computer code and tested on synthetic 3D EM data. The case histories include interpretation of a 3D magnetotelluric survey conducted in Hokkaido, Japan, and the 3D inversion of the tensor controlled‐source audio magnetotelluric data over the Sulphur Springs thermal area, Valles Caldera, New Mexico, U.S.A.
09
2000
1501
1513
10.1190/1.1444839
10.1190/1.1444839
https://library.seg.org/doi/10.1190/1.1444839

https://library.seg.org/doi/pdf/10.1190/1.1444839

http://geophysics.geoscienceworld.org/cgi/doi/10.1190/1.1444839
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