2006 Fiscal Year Final Research Report Summary
Quantitative assessment of deformation of upper crust based on paleomagnetism of widespread tephra and large-scale pyroclastic flow deposit
| Project/Area Number |
17540438
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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 |
Geology
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
ITOH Yasuto Osaka Prefecture University, Graduate School of Science, Associate Professor, 理学系研究科, 助教授 (20285315)
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| Project Period (FY) |
2005 – 2006
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| Keywords | geophysics / natural disaster / earthquake / paleomagnetism / active fault / geodesy / geology / disaster prevention |
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| Research Abstract |
In this study, field survey was conducted for widespread tephra, large-scale pyroclastic flow deposits and a Quaternary volcano in the central part of Honshu Island, Japan. Samples for paleomagnetic measurements were obtained from 39 sites. Remanent magnetization was measured by a spinner magnetometer, and stability of remanence was evaluated by progressive thermal and alternating-field demagnetization. Progressive acquisition of isothermal remanent magnetization (IRM) was conducted using a pulse magnetizer in order to estimate ferromagnetic minerals in rocks, and the estimation was verified through thermal demagnetization of orthogonal IRM. Available site-mean paleomagnetic directions were compiled for determination of high strain area, which was correlated with a deformation zone recently detected through geodetic studies of nationwide GPS array. Along with these study, fault motion and basin-forming history over 10 m.y. in an arc-arc junction (Hokkaido) and a seismogenic subduction zone (Pacific coast of northeast Japan) were clarified on the basis of interpretation of reflection seismic data, which gave a significant clue to understand tectonics in central Japan. We have precisely assessed short-term crustal deformation utilizing paleomagnetic method, which is generally applied for long-standing cumulative deformation between plates.
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Research Products
(7 results)
