Permalink : http://hdl.handle.net/2115/49078

JaLCDOI : 10.14943/gbhu.75.145

The first low-altitude airborne magnetic survey was performed over the summit area of Tarumae Volcano, southwestern Hokkaido, Japan. An unmanned autonomous helicopter was used as the platform for the magnetic survey. Obtained total field anomaly is inverted into a matrix of magnetized prisms, each of which has a uniform magnetization parallel to the present geomagnetic field. Magnetization in the summit atrio ranges from 3 to 8 A/m with an average of 5.3 A/m. The summit lava dome and its vicinity show relatively high magnetization, while the eastern to southwestern part of the atrio is less magnetized. Such variability may be attributed to the difference in magnetization between blocky lava and pyroclastic deposits, as well as to chemical demagnetization due to persistent fumarolic activity at several vents. From the viewpoint of an aeromagnetic survey, high positioning repeatability is one of the most advantageous features of such an unmanned autonomous helicopter. Optimized operation of the system would enable us to detect temporal changes associated with volcanic activity in the future.