Wide field electromagnetic sounding using y-component magnetic field with horizontal current dipole source
LUO Wei-Bin1(), DING Zhi-Jun2, GAO Shu-De3, ZHANG Xing2
1. Lanzhou Resources & Environment Voc-Tech College, College of Geology and Jewelry, Lanzhou 730000, China 2. Gansu Nonferrous Geological Survey Institute, Lanzhou 730000, China 3. Earthquake Administration of Gansu Province, Lanzhou 730000, China
Based on the formula system of the electromagnetic field of the horizontal electric dipole source on the layered earth surface, this paper proposes the wide field apparent resistivity of y-component magnetic field (Hy) using the modulus of impedance. The field components Ex, Hy, and Hz of the electromagnetic field with multiple source-receiver separations on the surface of layered geoelectric model are calculated. The wide field apparent resistivity with these three field components and Ex/Hy cagniard resistivity are calculated, and compared with the MT Cagniard resistivity spectrum curve of the model. It is suggested that the wide field apparent resistivity of Hy has a good response to the geoelectric model in the vast area of the equatorial array and the axial array of the horizontal electric dipole source, and it can be used for single component wide field electromagnetic sounding. The axial array wide field apparent resistivity of Hy is similar to that of the equatorial array wide field of the vertical magnetic field of Hz. In the low frequency band, the wide field apparent resistivity of Hy is similar to that of the Cagniard resistivity of the magnetotelluric sounding of the layered model. Under the condition of small source-receiver separation, the axial array wide field apparent resistivity of Hy can have a better response to the deep basement. The equatorial array and the axial array wide field apparent resistivity of the Ex component of the horizontal electric field will wholly enter "saturated area" in the low frequency band. For each resistivity definition method, the appropriate source-receiver separation is the premise to reflect the geoelectric characteristics better, and the multi source-receiver separation measurement is more conducive to reflecting the deep electrical characteristics.
罗维斌, 丁志军, 高曙德, 张星. 测量磁场水平分量Hy的电性源广域电磁测深法[J]. 物探与化探, 2021, 45(1): 46-56.
LUO Wei-Bin, DING Zhi-Jun, GAO Shu-De, ZHANG Xing. Wide field electromagnetic sounding using y-component magnetic field with horizontal current dipole source. Geophysical and Geochemical Exploration, 2021, 45(1): 46-56.
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