A new application of paleomagnetic viscous dating to tsunami boulders in Ishigaki Island, Japan
Project/Area Number |
25560173
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Research Category |
Grant-in-Aid for Challenging Exploratory Research
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Allocation Type | Multi-year Fund |
Research Field |
Natural disaster / Disaster prevention science
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Research Institution | Tohoku University |
Principal Investigator |
NAKAMURA Norihiro 東北大学, 理学(系)研究科(研究院), 准教授 (80302248)
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Co-Investigator(Kenkyū-buntansha) |
GOTO Kazuhisa 東北大学, 災害科学国際研究所, 准教授 (10376543)
SUGAWARA Daisuke 東北大学, 災害科学国際研究所, 助教 (50436078)
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Co-Investigator(Renkei-kenkyūsha) |
HATAKEYAMA Nobutatsu 岡山理科大学, 情報処理センター, 准教授 (80368612)
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Project Period (FY) |
2013-04-01 – 2015-03-31
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Project Status |
Completed (Fiscal Year 2014)
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Budget Amount *help |
¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000)
Fiscal Year 2014: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2013: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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Keywords | 津波 / 粘性残留磁気 / 石垣島 / 地磁気 / 年代推定 / 津波性巨礫 / 磁性緩和理論 |
Outline of Final Research Achievements |
We use temperature-dependent viscous remanent magnetization to estimate the emplacement age of tsunamigenic coral boulders along the shorelines of Ishigaki Island, Japan. The time of their deposition by tsunamis has been estimated using radiocarbon dating. Since the time when the coral skeletons were emplaced on the shorelines as boulders by destructive tsunami waves, a new viscous magnetization was partially overprinted in the boulder parallel to the present geomagnetic field. We analyzed two different boulders (200t dated at 2000 years old and 35t dated at 1771AD: Meiwa tsunami). The result implies that the 200 t coral boulder was immobile when the Meiwa tsunami struck the island and moved the 35 t boulder over the 1.0-km-wide reef. This suggests that the earlier tsunami was larger than the Meiwa tsunami. New application of Neel's theory to tsunamigenic coral boulders gives us an opportunity to ascertain the age and transportation mode of individual boulders in this area.
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Report
(3 results)
Research Products
(21 results)
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[Presentation] Three dimensional sedimentation processes and magnetic anisotropies of modern tsunami deposits in Minami-soma City, Japan2014
Author(s)
Kon, S., Iijima, Y., Nakamura, N., Sugawara, D., Goto, K.
Organizer
Asia Oceania Geosciences Society (AOGS)
Place of Presentation
札幌
Year and Date
2014-07-13
Related Report
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[Presentation] Paleomagnetic emplacement history of Tsunami boulder at Ishigaki Island, Japan2013
Author(s)
Sato, T., Nakamura, N., Goto, K., Nagahama, Y., Minoura, K.
Organizer
AOGS
Place of Presentation
Brisbane, Australia
Related Report
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[Presentation] The combination of anisotropy of anhysteretic remanent magnetization (AARM) and grain size data provide information about the hydrodynamic conditions of the tsunami deposits.2013
Author(s)
Kon, S., Nakamura, N., Sugawara, D., Goto, K., Iijima, Y.
Organizer
2nd G-EVER International Symposium and the 1st IUGS & SCJ International Workshop
Place of Presentation
仙台, 宮城
Related Report
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[Presentation] Anisotropy of anhysteretic remanent magnetization (AARM) reveals a cryptic flow fabric of tsunami deposits.2013
Author(s)
Kon, S., Nakamura, N., Sugawara, D., Goto, K., Chague-Goff, C., Goff, J.
Organizer
AGU Fall Meeting
Place of Presentation
San Francisco, USA
Related Report
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[Presentation] Viscous remanent magnetization of individual boulders in Ishigaki Island and its application to estimate the paleotsunami histories2013
Author(s)
Sato, T., Nakamura, N., Goto, K., Minoura, K., Nagahama, H.
Organizer
AGU Fall Meeting
Place of Presentation
San Francisco, USA
Related Report
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