1991 Fiscal Year Final Research Report Summary
The electrical conductivity structure beneath the Beppu-Shimabara graben
| Project/Area Number |
02640309
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | Saga University |
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Principal Investigator |
HANDA Shun Saga University, Faculty of Liberal Arts, 教養部, 教授 (70156529)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Yoshikazu Kyoto University, Faculty of Science, 理学部, 助手 (00025420)
SUZUKI Akira Saga University, Faculty of Liberal Arts, 教養部, 教授 (10025405)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Beppu-Shimagara graben / Conductivity anomaly / tectonics / GDS / MT |
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| Research Abstract |
The Beppu-Shimabara graben is an active region since the Quaternary volcanoes distribute and earthquakes occur frequently along this graben.
In order to make clear the electrical conductivity structure beneath the Beppu-Shimabara graben, the geomagnetic depth sounding (GDS) and the magnetotelluric (MT) observations including the ocean bottom electro-inagrietoineter observation or the shallow sea-floor of Ariake Sea, were made in the area along this graben. Induction vectors for shorter period than about 5 minutes obtained in the Shimabara Peninsula indicate that the high conductivity layer (HCL) under the ground possibly runs SSW to NNE in direction through- Tachibana Bay where is just the west of the Shimabara Peninsula. This unpiles that the HCL is not under the Beppu-Shimabara graben. Possibly the graben in the electrical structure is constructed by several IICLs which run across the graben as echelon faults.
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