Abstract
A two-dimensional forward and backward algorithm for the controlled-source audio-frequency magnetotelluric (CSAMT) method is developed to invert data in the entire region (near, transition, and far) and deal with the effects of artificial sources. First, a regularization factor is introduced in the 2D magnetic inversion, and the magnetic susceptibility is updated in logarithmic form so that the inversion magnetic susceptibility is always positive. Second, the joint inversion of the CSAMT and magnetic methods is completed with the introduction of the cross gradient. By searching for the weight of the cross-gradient term in the objective function, the mutual influence between two different physical properties at different locations are avoided. Model tests show that the joint inversion based on cross-gradient theory offers better results than the single-method inversion. The 2D forward and inverse algorithm for CSAMT with source can effectively deal with artificial sources and ensures the reliability of the final joint inversion algorithm.
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This work is jointly sponsored by the Fundamental Research Funds for the Central Universities and the National Natural Science Foundation of China (No. 41374078).
Wang Kun-Peng, he is a Ph.D. student at the School of Geophysics and Information Technology, China University of Geosciences (Beijing). He graduated with a B.S. in Geophysics from Chengdu University of Technology in 2011. He received an M.S. in Geodetection and Information Technology from Chengdu University of Technology in 2014. His main research interests are forward modeling and inversion of geoelectrical data.
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Wang, KP., Tan, HD. & Wang, T. 2D joint inversion of CSAMT and magnetic data based on cross-gradient theory. Appl. Geophys. 14, 279–290 (2017). https://doi.org/10.1007/s11770-017-0615-z
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DOI: https://doi.org/10.1007/s11770-017-0615-z