In geophysical exploration, almost all of the target physical properties are of vectors. To change the vector type physical properties measured at a point on a randomly moving coordinate system of the geophysical exploration tools into a fixed coordinate system, for example, geographical coordinate system, the attitude data of the tools are needed. Additionally, position data are also or more important for the next data processing than the attitude data as in many science and technology studies. In particular, when we do geophysical exploration in a natural tunnel where neither previously acquired survey data nor GNSS signals are available, a GNSS/INS system gives us the most useful attitude and position data for the post processing of the acquired geophysical exploration data. The GNSS/INS system outside of the tunnel initially aligns itself and calculates the relative azimuthal direction with respect to the axis of rotation of the earth (true north), the 2 axis dips, the position data with the help of the 3-component gyroscope, 3-component accelerometer, 3-component magnetometer and GNSS. Entering the tunnel, doing geophysical exploration, coming out of the tunnel, it calculates continuously the attitude and the position for each measurement point and the logger of the geophysical exploration tool writes the attitude and the position data and the measured geophysical data of the same point side by side with the mediation of the common time. We assembled a three components’ magnetic exploration system and named it Mag_GNSS/INS, in which we used an EGIS-N1000K of Navcours Co. for the GNSS/INS system. With that magnetic exploration system, aided by the GNSS/INS system, we could perform a three components’ magnetic exploration in Manjanggul, a Natural Tunnel on Jeju Island, Korea and could process the raw data acquired on the magnetometer sensor body’s random coordinates system into the data as if they were measured on geographical coordinates system through coordinates’ rotation. As the result we could get the N, E, Z components of the magnetic field as well as the total magnetic intensity in the natural lava tunnel. Such GNSS/INS system like EGIS-N1000K would let us possible to acquire the data in tensor type in the future for any geophysical exploration in which we measure the target geophysicla properties in vector type.

Keywords: Attitude data, Position data, three axis magnetometer, Euler rotation