2002 Fiscal Year Final Research Report Summary
Detection of the gravity changes in the subducting zone by means of precise gravity measurements
| Project/Area Number |
12640408
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体地球物理学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
HIGASHI Toshihiro Graduate School of Science, Instructor, 大学院・理学研究科, 助手 (90135517)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIMORI Kunio Graduate School of Science, Lecture, 大学院・理学研究科, 講師 (00025470)
FUKUDA Yoichi Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (30133854)
TAKEMOTO Shuzo Graduate School of Science, Professor, 大学院・理学研究科, 教授 (40027256)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Absolute Gravimeter / Gravity Change / Nankai Earthquake / Philippine Sea Plate / Cape Muroto |
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| Research Abstract |
Great earthquakes frequently occur at plate boundaries such as the Nankai Trough subducting the Philippine Sea Plate beneath the Eurasian Plate. We have attempted to detect absolute gravity changes caused by subducting plate.
New absolute gravity point was made at the Muroto Geophysical Observatory of University of Tokyo where located at the tip of a promontory of the Cape Murata in the Shikoku Island. We carried out the absolute gravity measurements to obtain the absolute change of the gravity values using the absolute gravimeter FG5#210. The absolute gravity measurements were performed about 1 week, in February 2001, February 2002 and September 2002, respectively. It was not recognized the gravity changes at absolute gravity point in these periods. However, considering to performance of FG-5 it will be detectable to absolute gravity changes by subsiding within several years.
Cape Mutoto in the Shikoku Island is subsiding recently at about 1 cm/year as a result the repeated leveling survey by the Geographical Survey Institute of Japan. The relative gravity measurements were also carried out around the Cape Muroto by employing La Coste & Romberg gravimeters on bench marks of the leveling routes as well as on the GPS continuous observation stations by the Geographical Survey Institute. Obtained results could not show the gravity changes more than precision of relative gravimetry.
Recently, destructive Nankai earthquake has been pointed out to occur in the near future. It is important to observe gravity changes employing absolute gravimeter at the Cape Muroto in the Shikoku Island for clarify the mechanism of subsiding plate.
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Research Products
(4 results)
