| Project/Area Number |
22K14122
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 17040:Solid earth sciences-related
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| Research Institution | Hiroshima University |
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Principal Investigator |
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| Project Period (FY) |
2022-04-01 – 2025-03-31
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| Project Status |
Granted (Fiscal Year 2023)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2024: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2023: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2022: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | Fault slip behavior / Main Frontal Thrust / Fault friction / Earthquake nucleation / Creep behavior / Himalayan Earthquakes / Rotary shear deformation / 回転せん断変形実験 / 変形微細組織 / 地震性すべり / クリープ性すべり / 主前縁断層 |
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| Outline of Research at the Start |
本研究の概要は、インド北部のPinjore市に露出するNahan断層が発達する岩石（「珪酸塩鉱物含有砂岩」と「石英砂岩」） を収集し、この岩石試料を用い回転せん断変形実験を行う。回転せん断変形実験の条件は、垂直応力： 2MPa、すべり速度： 0.01-3mm/s、0.1mm/s、1m/sとする。「珪酸塩鉱物含有砂岩」と「石英砂岩」に含有されている層状珪酸塩鉱物（緑泥石、イライト、カオリナイト）の微細組織を基にして、摩擦すべり特性を明らかにする。
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| Outline of Annual Research Achievements |
The objective of present research is to elucidate the weakening mechanism and fault-slip behavior of sandstone, which is a dominant rock type in both continental collisional zones (like the Himalaya) and accretionary complexes (like the Japanese Islands). Deformation experiment using rotary shear apparatus were conducted at 10 MPa effective normal stress and wet conditions on powdered sandstone samples and gouge samples, simulating shallow crustal deformation. Velocity weakening behavior were observed for the powdered sandstone and quartz-rich gouge sample. However, the gouge sample rich in illite show velocity strengthening behavior (or aseismic creep behavior).
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
As per plan, velocity step experiments in wet condition (simulating natural conditions) has already been conducted. The reproducibility of the low velocity experiments were also verified.
A set of single velocity experiment and experiment at seismic velocity has also been completed. The mineralogical characterization using XRD and SEM-EDS has also been achieved.
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| Strategy for Future Research Activity |
At present we completed the mineralogical and microstructural characterization of the recovered samples from the rotary shear deformation experiments. In the final year of the project we plan to do additional set of creep experiments <10 μm/s and compare the frictional behavior and microstructures with the rotary shear experiments. This experiments will provide insights of the frictional behavior of the sandstone and gouge rocks of shallow crust (Nahan Thrust) over a range of slip velocities (creep-to-seismic velocities).
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