THE POWERLINE INTERFERENCE IN THE MAGNETO-ELECTROTELLURIC EXPLORATION
LIANG Sheng-xian1,2, ZHANG Sheng-ye1, HUANG Li-shan3, SUN Shi-chao1
1. Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China; 2. Chengdu Center, China Geological Survey , Chengdu 610081, China; 3. Guilin Research Institute of Geology for mineral Resources, Guilin 541004, China
Abstract：Because the power frequency is complex and will produce heavy electromagnetic noise in magnetotelluric sounding, the distortion of electromagnetic signal and the troubles in data processing and interpretation may occur under the condition of serious disturbance. In order to provide reference for weakening and suppressing the interference, the authors set the line current source above the ground level to simulate the power lines, inferred the formula and calculated the electromagnetic field. The results show that, even if the transmission distance is 500 m, the disruption field can still completely submerge target signals. However, this interference field has its fixed features, so the following conclusions can be drawn through the calculation and discussion of these features:On the one hand, the electromagnetic field generated by power lines is a plane wave which can be converted into useful signal outside a wavelength; On the other hand, within the wavelength, the situation that apparent resistivity in both directions encounters interference at the same time can be avoided by arranging the electrodes according to the direction of the electric field and magnetic field.
