A method for calculating background resistivity based on total magnetic intensity in ground-airborne frequency domain electromagnetic exploration in areas with topographic relief

Abstract Ground-airborne frequency domain electromagnetic (GAFDEM) is an important tool for mineral resource exploration and geological surveys in complex mountainous areas. The rapid and high-precision calculation of background resistivity is the foundation for high-resolution imaging. Due to the influence of attitude noise, the current accuracy of background resistivity calculations is not high. Furthermore, when the measurement area is large and the terrain is complex, the need to establish a terrain model for the measurement area leads to a decrease in efficiency. To solve the above problems, this paper proposes a method to calculate the background resistivity using the total magnetic intensity. Firstly, the magnetic field component is analyzed for its ability to identify anomalies, then the effects of transmitting frequency and source-receiver distance parameters are analyzed, and finally, simulation experiments and field experiments are conducted. Simulation experiments show that the method of calculating background resistivity using total magnetic intensity can accurately calculate the background resistivity of the double anomaly model and the model with topographic relief compared with the current method. Field experiments show that compared with the current method, the total magnetic intensity method of calculating background resistivity is not affected by attitude noise, and the results of background resistivity calculation are consistent with the real results with higher accuracy. The method in this paper supports GAFDEM to realize high-resolution and fast exploration of underground structures.