Abstract
A new versatile deep-sea three-component magnetometer has been developed in order to investigate fine magnetic structures of the oceanic crust. The system includes a tri-axis fluxgate magnetometer, an attitude detection meter and a depth meter. The system is operated with an AC or battery power supply. The magnetometer and the attitude detection meter measure the magnetic field vectors and the roll and pitch of the system every 0.5 or 1 sec. Vector geomagnetic anomalies are calculated from these data and yaw data measured by an external gyro system. Observations with the battery power supply can be made continuously for as long as 18 hours for 0.5 sec sampling and 36 hours for 1 sec sampling. The depth meter provides the pressure data and the temperature data every 3.5 sec. This system operates to a maximum depth of 6,500 m. In addition to the above performance, it has versatile usage which enables us to make the following three types of observations using the same instruments: a stand-alone observation; a cooperative observation with another deep-sea system; an on-board observation. We successfully measured the geomagnetic field near the ocean bottom around the Mid-Atlantic Ridge and the west Kane Transform Fault using our magnetometer system mounted on the submersible "Shinkai 6500" in 1994. We will here explain the present system and show some of the results obtained in 15 dives by the "Shinkai 6500".
