| Magnetotellurics (MT) is widely applied in production process because of its convenient construction, low cost and high resistivity. There are three reasons for the fast development of MT in recent decades:Firstly, it owns a lot of advantages such as large exploration depth range, high resolution, light equipment, low cost and wide use;secondly, it meets the objective needs:researches on geodynamics, plate motion, earthquake forecasting and resource exploration need the Earth’s interior temperature distribution which is closely related to the underground resistivity distribution provided by MT method; thirdly, the external conditions are well enough:the development of electronic technology provides the MT method with equipments with high sensitivity and high-resolution as well as other geophysical methods provide rich analytical tools. MT method has become one of the most important methods in comprehensive geophysical exploration, and widely used in the crust and upper mantle research, local and the large regional tectonics research, earthquake disaster research, mineral resources and geothermal exploration, geodynamics and plate motion, physical properties of the lithosphere and asthenosphere.Magnetotellurics, however, also has unavoidable defects. Due to the limitations of the source characteristics of the natural field, magnetotellurics method is only suitable for low-frequency collection with lower resolution, which decides that the method can only use for deep macro exploration. Furthermore, the instability of the natural field source results in certain limitations of the MT method.EH-4electromagnetic sounding method (known as high-frequency magnetotelluric sounding method) integrated the characteristics of magnetotelluric sounding method and the artificial field source (configured with magnetic dipole emission source) to solve the shortage of signals caused by magnetotelluric in the1kHz to5kHz silent area and to ensure the stability of the signal source, which makes it become an incomparable electromagnetic method. EH-4electromagnetic sounding method also has the following features:ensuring the exploration from the shallow to the deep, speeding up the exploration process and improving work efficiency as well as strengthening the anti-interference ability, which ensures the quality of the observation. In recent years, the EH-4electromagnetic sounding method has been widely applied in our survey of groundwater, the environmental characterization of the subsurface investigation, mineral exploration and geothermal exploration and engineering researches. During field production process, outside interference, especially today’s increasingly complex human environment, has brought many difficulties to the practical use. The paper mainly discusses the methods of data collecting and documents processing in complex electromagnetic environment. The article briefly summarizes the working principles of the EH-4sounding system, and introduces the characteristics of the device as well as field work arrangement. Since EH-4sounding system is easily affected by external electromagnetic interference, the paper has made a systematical research on its documents processing after briefly analyzed the features of various interference signals,then,put forward the relevant solutions. The research, based on the MATLAB, inverts the EH-4data with the help of practical cases, program,mainly includes reading and building the Z-file,generating the specific files,such as elevation files. Finally, the method in the paper will be demonstrated with examples. |
