Geomagnetic surveys on sea by aircraft and ship.

In accordance with the resolution adopted at the XI th General Assembly of I. U. G. G., 1957, the program of magnetic surveys on sea has been progressed in Japan. For the aeromagnetic survey on sea, an airborne magnetometer with saturable inductor was developed by the Tohoku University team of the writers, and was put to practical surveys in Boso-district in February, 1958, around Osima Island (Izu) area in July, 1958, and in the Izu Syoto (Islands) in August,1959. The results of the first and second surveys were reported previously. The third survey was carried out by " Beachcraft No. 502 " of the Maritime Safety Board, with flight elevation of 3000 m above the sea level, measuring the vertical component of the earth's magnetic field to clarify that the most remarkable anomaly was associated with volcanoes on the Izu Syoto. For the magnetic survey at sea surface, a shipborne magnetometer, designed by the Tohoku University team of the writers, was employed on a survey ship Takuyo of the Hydrographic Office around the Sagami Nada near Izu Hanto (Peninsula), in January, 1960. The heart of this magnetometer is a saturable inductor mounted on a gimbal system. In order to avoid the magnetic disturbance by the vessel, the instrument was hung at about 40-meter depth beneath her body. From results of the survey, two remarkable anomalies were observed around Ito and Okinoyama, respectively. It is found that the anomalous anomaly near Ito is associated with submarine volcanoes, and the· anomaly around Okinoyama belongs to the submarine topographic configuration. We also studied the magnetism of a steel vessel. In this paper, the general feature of magnetic fields around an iron ship is investigated, especially, from the standpoint of detecting it magnetically. Magnetic moment of the steel vessel Takuyo was obtained from the results of magnetic survey around her body by assuming the vessel as a uniformly magnetized prolate spheroid.

Bibliographic Details

Main Authors:	Kato, Yoshio, Utashiro, Shinkichi, Matuo, Masayuki, Takagi, Akio, Terajima, Makoto, Ito, Miyoshi
Format:	Journal Contribution biblioteca
Language:	English
Published:	1960
Online Access:	http://hdl.handle.net/1834/16934
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