13. 最近の櫻島火山の活動に就いて(Ⅱ) : 新熔岩流の帶磁と傾斜變化

概要

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A survey of geomagnetic dip was repeated by the dip circle used in the first survey in 1939. Remarkable changes in dip were not observed at any place in the Sakura-zima Island but one situated quite near the new lavaflow. By another dip-survey across the north side of the newlava, it was found that the lava was magnetized in the direction of the present geomagnetic field as a whole, and its intensity of magnetization calculated from the observed anomaly was 0.005±0.001 e.m.u. Measurement of tilt of the ground was also repeated in the same manner as in April. Most of bench-marks having bean destroyed, during Apr.～Oct., only three groups of them remained. At these stations, the ground tilted towards the same direction as before(See Fig.4), and its daily rate of the tilt decreased to 1/9 of that of April. The topographic distribution of direction of tilt suggests that the island consists of more than three blocks. A topographic survey near the new crater was carried out by a mountain barometer and a clinometer.
東京大学地震研究所,Earthquake Research Institute, University of Tokyo,地震研究所の論文
1948-06-30