The Characteristic and Prospecting Technology of the Marine Magnetotelluric Field
Deng Ming 1,2 Du Gang2 Zhang Qisheng2 Yu Ping3 Deng Jingwu2 1(Geo-dectection Laboratory, Ministry of Education ,Beijing 100083, China) 2(School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China) 3(Technology Institute, Guangzhou Marine Geological Survey, Guangzhou 510760, China)
Geologic structure under the seafloor can be known by prospecting the marine magnetotelluric field. Advanced instrument is needed for this purpose. The marine environment is special and complex: it attenuates the magnetotelluric signal, destroys the equipments and makes the measurement uncontrollable. To solve these problems the characteristic of the marine magnetotelluric field is analyzed. The field distribution under the seafloor can be generally deduced by prospecting the two horizontal geoelectric components and the three geomagnetic components that are perpendicular to each other. In the design of the instruments the data collection circuit is composed of embedded computer, 24-Bit A/D and flash memory, and the signal acquisition is automatic. Special pressurized capsule is used to protect electronic devices and the instruments are reclaimed by sonar control method. By using the instruments, the magnetotelluric data have been collected for the first time in Chinese sea area and the acquired data are verified to meet the theoretics.