Three-dimensional topography corrections of magnetotelluric data |
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Authors: | Myung Jin Nam Hee Joon Kim Yoonho Song † Tae Jong Lee Jung Hee Suh |
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Institution: | Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin, TX 78712;, USA Department of Environmental Exploration Engineering, Pukyong National University, Busan 608-737;, Korea Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350;, Korea. E-mail: Deceased, Formerly Department of Civil, Urban and Geosystem Engineering, Seoul National University, Seoul 151-744;, Korea |
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Abstract: | Topographic effects due to irregular surface terrain may prevent accurate interpretation of magnetotelluric (MT) data. Three-dimensional (3-D) topographic effects have been investigated for a trapezoidal hill model using an edge finite-element method. The 3-D topography generates significant MT anomalies, and has both galvanic and inductive effects in any polarization. This paper presents two different correction algorithms, which are applied to the impedance tensor and to both electric and magnetic fields, respectively, to reduce topographic effects on MT data. The correction procedures using a homogeneous background resistivity derived from a simple averaging method effectively decrease distortions caused by surface topography, and improve the quality of subsurface interpretation. Nonlinear least-squares inversion of topography-corrected data successfully recovers most of structures including a conductive or resistive dyke. |
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Keywords: | Numerical solutions Magnetotelluric |
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