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Gravity at sea--A memoir of a marine geophysicist.

Tomoda Y - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2010)

Bottom Line: Professor Chuji Tsuboi made a number of unsuccessful attempts at developing a gravity meter that can be operated on a normal surface ship by reducing the noise by minimizing the motion of the gravity meter through a mechanical design.I have chosen a new approach toward the measurements of gravity on a surface ship by simplifying the mechanical part using a string gravity meter that was installed directly on a vertical gyroscope in combination with the numerical and/or electronic reduction of noises.The results reveal the fine structures of gravity field in and around trenches that provide important clues as to a number of geodynamic issues including the nature of the trench-trench interaction and the interaction of trenches with seamounts.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan. fujimoto@aob.gp.tohoku.ac.jp

ABSTRACT
A history of studies on the gravity measurements at sea in Japan is reviewed with an emphasis on the contribution of the author. The first successful measurements at sea were made in 1923 by Vening Meinesz in the Netherlands using the pendulum apparatus installed in a submarine. However, the gravity measurements using a submarine are not convenient because the access to a submarine is limited. Professor Chuji Tsuboi made a number of unsuccessful attempts at developing a gravity meter that can be operated on a normal surface ship by reducing the noise by minimizing the motion of the gravity meter through a mechanical design. I have chosen a new approach toward the measurements of gravity on a surface ship by simplifying the mechanical part using a string gravity meter that was installed directly on a vertical gyroscope in combination with the numerical and/or electronic reduction of noises. With this gravity meter TSSG (Tokyo Surface Ship Gravity Meter), we firstly succeeded in measuring gravity at sea onboard a surface ship in July 1961 and the measurements have been extended to the northwestern Pacific and beyond. The results reveal the fine structures of gravity field in and around trenches that provide important clues as to a number of geodynamic issues including the nature of the trench-trench interaction and the interaction of trenches with seamounts.

Show MeSH
The first model of the string gravity meter TSSG-60. A vertical gyroscope for the horizontal navigation of an airplane was remodeled and the string gravity meter was installed directly on it. The string was placed in an electronically controlled housing of constant temperature. With this gravity meter, we succeeded in measuring gravity at sea from Tokyo to Miyakejima Island in July 1961. Length of the scale in the photograph is 20 cm.
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fig4a: The first model of the string gravity meter TSSG-60. A vertical gyroscope for the horizontal navigation of an airplane was remodeled and the string gravity meter was installed directly on it. The string was placed in an electronically controlled housing of constant temperature. With this gravity meter, we succeeded in measuring gravity at sea from Tokyo to Miyakejima Island in July 1961. Length of the scale in the photograph is 20 cm.

Mentions: One day, when I looked around the electric junk stores in the street of Kanda, I happened to find a curious apparatus. The device seemed to be a vertical gyroscope for an airplane. The owner of the junk store told me that these were vertical gyroscopes for horizontal navigation of the bombers used in the Korean War. The price of a complete set was 6,000 yen. I bought four sets of them. They were products of “Honeywell”. I disassembled one set completely, and investigated how it works. Professor Hisashi Kinbara at the First High School (present Division of General Education, University of Tokyo) introduced me to his colleague Professor Matao Sanuki who was a specialist of aviation instruments. He took it to Nihon Kouku Denshi Co. (Japan Aviation Electronics Industry) and brought it back to our laboratory in virtually brand new condition. I used it for the prototype shipboard gravity meter as is shown in Fig. 6.


Gravity at sea--A memoir of a marine geophysicist.

Tomoda Y - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2010)

The first model of the string gravity meter TSSG-60. A vertical gyroscope for the horizontal navigation of an airplane was remodeled and the string gravity meter was installed directly on it. The string was placed in an electronically controlled housing of constant temperature. With this gravity meter, we succeeded in measuring gravity at sea from Tokyo to Miyakejima Island in July 1961. Length of the scale in the photograph is 20 cm.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037522&req=5

fig4a: The first model of the string gravity meter TSSG-60. A vertical gyroscope for the horizontal navigation of an airplane was remodeled and the string gravity meter was installed directly on it. The string was placed in an electronically controlled housing of constant temperature. With this gravity meter, we succeeded in measuring gravity at sea from Tokyo to Miyakejima Island in July 1961. Length of the scale in the photograph is 20 cm.
Mentions: One day, when I looked around the electric junk stores in the street of Kanda, I happened to find a curious apparatus. The device seemed to be a vertical gyroscope for an airplane. The owner of the junk store told me that these were vertical gyroscopes for horizontal navigation of the bombers used in the Korean War. The price of a complete set was 6,000 yen. I bought four sets of them. They were products of “Honeywell”. I disassembled one set completely, and investigated how it works. Professor Hisashi Kinbara at the First High School (present Division of General Education, University of Tokyo) introduced me to his colleague Professor Matao Sanuki who was a specialist of aviation instruments. He took it to Nihon Kouku Denshi Co. (Japan Aviation Electronics Industry) and brought it back to our laboratory in virtually brand new condition. I used it for the prototype shipboard gravity meter as is shown in Fig. 6.

Bottom Line: Professor Chuji Tsuboi made a number of unsuccessful attempts at developing a gravity meter that can be operated on a normal surface ship by reducing the noise by minimizing the motion of the gravity meter through a mechanical design.I have chosen a new approach toward the measurements of gravity on a surface ship by simplifying the mechanical part using a string gravity meter that was installed directly on a vertical gyroscope in combination with the numerical and/or electronic reduction of noises.The results reveal the fine structures of gravity field in and around trenches that provide important clues as to a number of geodynamic issues including the nature of the trench-trench interaction and the interaction of trenches with seamounts.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan. fujimoto@aob.gp.tohoku.ac.jp

ABSTRACT
A history of studies on the gravity measurements at sea in Japan is reviewed with an emphasis on the contribution of the author. The first successful measurements at sea were made in 1923 by Vening Meinesz in the Netherlands using the pendulum apparatus installed in a submarine. However, the gravity measurements using a submarine are not convenient because the access to a submarine is limited. Professor Chuji Tsuboi made a number of unsuccessful attempts at developing a gravity meter that can be operated on a normal surface ship by reducing the noise by minimizing the motion of the gravity meter through a mechanical design. I have chosen a new approach toward the measurements of gravity on a surface ship by simplifying the mechanical part using a string gravity meter that was installed directly on a vertical gyroscope in combination with the numerical and/or electronic reduction of noises. With this gravity meter TSSG (Tokyo Surface Ship Gravity Meter), we firstly succeeded in measuring gravity at sea onboard a surface ship in July 1961 and the measurements have been extended to the northwestern Pacific and beyond. The results reveal the fine structures of gravity field in and around trenches that provide important clues as to a number of geodynamic issues including the nature of the trench-trench interaction and the interaction of trenches with seamounts.

Show MeSH