An extended theory of paleomagnetic viscous dating and its application to tsunami boulders in Japan and Tonga
| Project/Area Number |
15H02986
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Natural disaster / Disaster prevention science
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| Research Institution | Tohoku University |
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Principal Investigator |
Nakamura Norihiro 東北大学, 高度教養教育・学生支援機構, 教授 (80302248)
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| Co-Investigator(Kenkyū-buntansha) |
後藤 和久 東北大学, 災害科学国際研究所, 准教授 (10376543)
菅原 大助 東北大学, 災害科学国際研究所, 助教 (50436078)
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Project Status |
Completed (Fiscal Year 2017)
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| Budget Amount *help |
¥17,680,000 (Direct Cost: ¥13,600,000、Indirect Cost: ¥4,080,000)
Fiscal Year 2017: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2016: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2015: ¥9,880,000 (Direct Cost: ¥7,600,000、Indirect Cost: ¥2,280,000)
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| Keywords | viscous remanence / tsunami disaster / fault gouge / 粘性残留磁気 / 地磁気 / 津波石 / 巨礫 / 津波起源巨礫 / 津波性巨礫 / 津波 / 活断層 |
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| Outline of Final Research Achievements |
We proposed a new paleomagnetic method to determine the age of emplacement of tsunamigenic boulders, but some boulders showed an anomalously older age than the one of radioisotope method. We have used Neel's theory of magnetic relaxation (i.e., exponential relaxation law), but the theory disagrees with previous laboratory data for magnetic relaxation. Using a stretched exponential relaxation law with variable power exponents, we found that almost all previous data fit this law. This theoretical extension also explained the problem of older ages. However, we still need to answer the further problem that how do we determine the power exponent from individual boulders. In this project, we published two other papers that related to this research. One is that anisotropy of magnetic susceptibility does not always show a paleocurrent flow of sandy tsunami deposits. The other is that slip zones in Nojima fault zone experienced a temperature rise over 400 C using scanning magnetic microscopes.
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Report
(4 results)
Research Products
(58 results)
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[Journal Article] Inverse magnetic fabric in unconsolidated sandy event deposits in Kiritappu Marsh, Hokkaido, Japan2017
Author(s)
Kon, S., Nakamura, N., Nishimura, Y., Goto, K., and Sugawara, D.
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Journal Title
Sedimentary Geology
Volume: 349
Pages: 112-119
DOI
Related Report
Peer Reviewed / Acknowledgement Compliant
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[Presentation] トンガの津波石について2016
Author(s)
中村教博、佐藤哲郎、猪野楓
Organizer
第7回津波堆積物研究会
Place of Presentation
ふじのくに地球環境史ミュージアム（静岡県静岡市）
Year and Date
2016-08-10
Related Report
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[Presentation] Measurements of the permitivity, density, and volume fraction of crack around artificial impact crater2016
Author(s)
K. Ishiyama, Kumamoto, A., Takagi, Y., Nakamura, N., and Hasegawa, S.
Organizer
Lunar and Planetary Science Conference
Place of Presentation
Arizona, USA
Year and Date
2016-03-22
Related Report
Int'l Joint Research
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[Presentation] GP31A-1383, An extended magnetic viscous relaxation dating for calibrating an older age: an example of tsunamigenic coral boulders in Ishigaki Island, Japan2015
Author(s)
Sato, T., Nakamura, N., Goto, K., Kumagai, Y., Minoura, K., Nagahama, H.
Organizer
American Geophysical Union fall meeting
Place of Presentation
San Francisco
Year and Date
2015-12-16
Related Report
Int'l Joint Research
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