Semi-brittle behavior of olivine under the conditions of mantle transition zone
| Project/Area Number |
18K18788
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 17:Earth and planetary science and related fields
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| Research Institution | Ehime University |
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Principal Investigator |
Ohuchi Tomohiro 愛媛大学, 地球深部ダイナミクス研究センター, 講師 (60570504)
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| Project Period (FY) |
2018-06-29 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000)
Fiscal Year 2019: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2018: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
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| Keywords | 深発地震 / カンラン石 / 相転移 / マイクロクラック / 断層 / アコースティックエミッション / AE / 微小破壊音 / アコースティック・エミッション / マントル遷移層 |
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| Outline of Final Research Achievements |
To investigate the role of phase transformation of olivine on deep-focus earthquakes, I conducted uniaxial deformation experiments on dunite and at pressures 10-17 GPa and temperatures 700-1000 degC using a D-DIA apparatus. Acoustic emissions were monitored using the “micro-seismic monitoring system” which has been newly developed by this research program. Ductile deformation is dominant at temperatures exceeding 950 degC. Numerous mode-I microcracks occurred at lower temperatures (< 900 degC). Microcracking frequently occurred at higher pressures which allow phase transformation of olivine, suggesting that the phase transformation triggers microcracking. At 900 degC, corresponding to the threshold temperature for brittle-ductile transition of olivine, occurrence of a few faults was sometimes observed. Fault slip associated rupture. In summary, deep-focus earthquakes could be triggered when phase transformation of olivine proceeds at the temperatures of brittle-ductile transition.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究にて行った、地球の深さ300-500kmに位置するスラブ深部の温度圧力条件下における岩石破壊実験は世界初の試みである。これまで、深発地震発生の素過程に関する研究分野をリードしてきたのは欧米の研究グループであった中、本研究の「マイクロAE測定システム」は世界で初めてスラブ深部の温度圧力条件下における微小破壊音測定を可能とした。これは当該分野にて世界をリードしていけるブレークスルーであり、当システムを用いた研究を今後も継続していくことは、我が国においては防災への応用といった観点からも非常に大きい意義をもつ。
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Report
(3 results)
Research Products
(11 results)
