Browse > Article
http://dx.doi.org/10.7582/GGE.2011.14.2.164

Modeling of Magnetotelluric Data Based on Finite Element Method: Calculation of Auxiliary Fields  

Nam, Myung-Jin (Department of Energy and Mineral Resources Engineering, Sejong University)
Han, Nu-Ree (Department of Energy and Mineral Resources Engineering, Sejong University)
Kim, Hee-Joon (Department of Energy Resources Engineering, Pukyong National University)
Song, Yoon-Ho (Groundwater and Geothermal Division, Korea Institute of Geoscience and Mineral Resources)
Publication Information
Geophysics and Geophysical Exploration / v.14, no.2, 2011 , pp. 164-175 More about this Journal
Abstract
Using natural electromagnetic (EM) fields at low frequencies, magnetotelluric (MT) surveys can investigate conductivity structures of the deep subsurface and thus are used to explore geothermal energy resources and investigate proper sites for not only geological $CO_2$ sequestration but also enhanced geothermal system (EGS). Moreover, marine MT data can be used for better interpretation of marine controlled-source EM data. In the interpretation of MT data, MT modeling schemes are important. This study improves a three dimensional (3D) MT modeling algorithm which uses edge finite elements. The algorithm computes magnetic fields by solving an integral form of Faraday's law of induction based on a finite difference (FD) strategy. However, the FD strategy limits the algorithm in computing vertical magnetic fields for a topographic model. The improved algorithm solves the differential form of Faraday's law of induction by making derivatives of electric fields, which are represented as a sum of basis functions multiplied by corresponding weightings. In numerical tests, vertical magnetic fields for topographic models using the improved algorithm overcome the limitation of the old algorithm. This study recomputes induction vectors and tippers for a 3D hill and valley model which were used for computation of the responses using the old algorithm.
Keywords
3D; basis function; edge finite elements; MT; modeling; topography;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
연도 인용수 순위
1 Yee, K. S., 1966, Numerical solution of initial boundary value problems involving Maxwell's equation in isotropic media, IEEE Trans. Anten. Prop., AP-14, 302-307.
2 Zhdanov, M. S., Varentsov, I. M., Weaver, J. T., Golubev, N. G., and Krylov, V. A., 1997, Methods for modeling electromagnetic fields. Results from COMMEMI-the international project on the comparison of modeling methods for electromagnetic induction, J. Applied Geophys., 37, 133-271.   DOI   ScienceOn
3 Zonge, K. L., and Hughes, L. J., 1991, Controlled source audiofrequency magnetotellurics, in Nabighian, M. N., Ed., Electromagnetics in Applied Geophysics, Vol II, Soc. Expl. Geophys., 713-809.
4 Unsworth, M. J., Jones, A. G., Wei, W., Marquis, G., Gokarn, S. G., Spratt, J. E., and the INDEPTH0MT tem, 2005, Crustal rheology of the Himalaya and Southern Tibet inferred from magnetotelluric data, Nature, 438, 78-81.   DOI   ScienceOn
5 Vozoff, K., 1991, The magnetotelluric method, in Nabighian M. N., Ed., Electromagnetic methods in applied geophysics, Soc. Explor. Geophys., Vol. II, 641-711.
6 Wang, T., and Hohmann, G. W., 1993, A finite difference, timedomain solution for three-dimensional electromagnetic modeling, Geophysics, 58, 797-809.   DOI
7 Wannamaker, P. E., Stodt, J. A., and Rijo, L., 1986, Two-dimensional topographic responses in magnetotelluric modeled using finite elements, Geophysics, 51, 2131-2144.   DOI   ScienceOn
8 Smith, J. T., 1996, Conservative modeling of 3-D electromagnetic fields, Part II: Biconjugate gradient solution and an accelerator, Geophysics, 61, 1319-1324.   DOI   ScienceOn
9 Siripunvaraporn, W., Egbert, G., Lenbury, Y., and Uyeshina, M., 2005, Three-dimensional magnetotelluric inversion: dataspace method Phys. Earth Planet. Inter. 150, 3-14.   DOI   ScienceOn
10 Ting, S. C., and Hohmann, G. W., 1981, Integral equation modeling of three-dimensional magnetotelluric response, Geophysics, 46, 182-197.   DOI   ScienceOn
11 Nedelec, J. C., 1980, Mixed finite elements in R3, Numr. Math., 35, 315-341.   DOI   ScienceOn
12 Reddy, I. K., Rankin, D., and Phillips, R. J., 1977, Threedimenstional modeling in magnetotelluric and magnetic variational sounding, Geophys. J. Roy. Astr. Soc., 51, 313- 325.
13 Sasaki, Y., 1999, Three-dimensional frequency-domain electromagnetic modeling using the finite-difference method, Butsuri- Tansa, 52, 421-431. (in Japanese with English abstract)
14 Nam, M. J., Kim, H. J., Song, Y., Lee, T. J., Son, J. S., and Suh, J. H., 2007a, 3D magnetotelluric modeling including surface topography, Geophysical Prospecting, 55, 277-287.   DOI   ScienceOn
15 Nam, M. J., Kim, H. J., Song, Y., Lee, T. J., and Suh, J. H., 2007b, Effects of 3D topography on magnetotelluric responses, Mulli-Tamsa, 10, 275-284.
16 Nam, M. J., Kim, H. J., Song, Y., Lee, T. J., and Suh, J. H., 2009, Three-dimensional topographic and bathymetric effects on magnetotelluric responses in Jeju Island, Korea, Geophys. J. Int., 176, 457-466.   DOI   ScienceOn
17 Lee, T. J., Han, N., and Song, Y., 2010, Magnetotelluric survey applied to geothermal exploration: An example at Seokom Island, Korea, Exploration Geophysics, 41, 61-28.   DOI   ScienceOn
18 Mackie, R. L., Smith, J. T., and Madden, T. R., 1994, Threedimensional electromagnetic modeling using finite difference equations: The magnetotelluric example, Radio Science, 29, 923-935.   DOI   ScienceOn
19 Mackie, R., Watts, D. M., and Rodi, W., 2007, Joint 3D inversion of marine CSEM and MT data, SEG expanded abstract, 574-578.
20 Han, N., Nam, M. J., Kim, H. J., Song, Y., and Suh, J. H., 2009, A comparison of accuracy and computation time of threedimensional magnetotelluric modeling algorithms, J. Geophys. Eng., 6, 136-145.   DOI   ScienceOn
21 Honkura, Y., Niblett, B. R., and Kurtz, R. D., 1976, Changes in magnetic and telluric fields in a seismically active region of eastern Canada: Preliminary results of earthquake prediction studies, Tectonophysics, 34, 219-230.   DOI   ScienceOn
22 Hoversten, M. G., Newman, G. A., Geier, N., and Flanagan, G., 2006, 3D modeling of a deepwater EM exploration survey, Geophysics, 71, G239-G248.   DOI   ScienceOn
23 Commer, M., and Newman, G. A., 2009, Three-dimensional controlled-source electromagnetic and magnetotelluric joint inversion, Geophysical Journal International, 178, 1305-1316.   DOI   ScienceOn
24 Constable, S., and C. Weiss, 2006, Mapping thin resistors and hydrocarbons with marine EM methods: Insights from 1D modeling, Geophysics, 71, G43-G51.   DOI   ScienceOn
25 Druskin, V., and Knizhnerman, L., 1994, A spectral approach to solving three-dimensional diffusion Maxwell's equation in the time and frequency domains, Radio Science, 29, 937-953.   DOI   ScienceOn
26 Goldstein, N. E., 1988, Subregional and detailed exploration for geothermal-hydrothermal resources, Geotherm. Sci. Tech., 1, 303-431.
27 손정술, 송윤호, 정승환, 서정희, 2002, 벡터 유한 요소를 이용한 고주파수 3차원 전자탐사 모델링, 물리탐사, 5, 280-290.
28 이태종, 한누리, 고광범, 황세호, 박권규, 김형찬, 박용찬, 2010, 이산화탄소 지중저장 Pilot 선정을 위한 의성지역 MT 탐사, 지구물리와 물리탐사, 12, 281-288.
29 Berdichevsky, M. N., and Dmitriev, V. I., 2002, Magnetotellurics in the context of the theory of ill-posed problems, Soc. Explor. Geophys.
30 남명진, 2006, MT 탐사의 3차원 지형효과 분석 연구, 서울대학교 박사학위 논문.
31 남명진, 김희준, 송윤호, 이태종, 서정희, 2007, MT 탐사의 3차원 지형효과, 물리탐사, 10, 275-284.