| Project/Area Number |
19340147
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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 |
Geology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SHIMIZU Ichiko The University of Tokyo, 大学院・理学系研究科, 助教 (40211966)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAGA Takehiko 東京大学, 地震研究所, 助教 (10444077)
MICHIBAYASHI Katsuyoshi 静岡大学, 理学部, 準教授 (20270978)
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| Project Period (FY) |
2007 – 2009
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| Project Status |
Completed (Fiscal Year 2009)
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| Budget Amount *help |
¥19,370,000 (Direct Cost: ¥14,900,000、Indirect Cost: ¥4,470,000)
Fiscal Year 2009: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2008: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥15,730,000 (Direct Cost: ¥12,100,000、Indirect Cost: ¥3,630,000)
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| Keywords | レオロジー / 地殼マントル物質 / 沈み込み帯 / 中深発地震 / 岩石レオロジー / 高温高圧変形実験 / 含水量 / 差応力 / 脆性-延性転移 / 固体圧試験機 / 蛇紋岩 / 脱水反応 / 沈み込みスラブ / 地震 / アンチゴライト / 応力-歪曲線 / 固体圧式変形試験機 / 応力 / 脆性一延性 / 地震発生構 / 流体 / 後方電子散乱増 |
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| Research Abstract |
A popular hypothesis for the occurrence of double seismic zones, observed at the intermediate depth of about 50-200km, is dehydration embrittlement of the serpentinized slab mantle. The weakening of serpentinite was attributed to excess pore fluid pressure caused by dehydration reaction of serpentine. However, the confining pressure of these experiments using gas-medium apparatus was limited up to 500MPa (corresponding to 15km depth). It is questionable if the same mechanism could be effective in subducting slabs at higher pressures. We conducted constant strain-rate experiments of serpentinite using a solid-medium deformation apparatus and found that the yield strength of serpentinites drastically decreased when dehydration reaction proceeded. This phenomena, named "dehydration weakening", would be a key to understand seismogenic processes in the serpentinized mantle slabs.
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