| Project/Area Number |
08454120
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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 |
固体地球物理学
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| Research Institution | Earthquake Research Institute, University of Tokyo |
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Principal Investigator |
SHIMAMOTO Toshihiko Earthquake Research Institute, University of Tokyo, Professor, 地震研究所, 教授 (20112170)
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| Co-Investigator(Kenkyū-buntansha) |
UMEDA Yasuhiro Disaster Prevention Research Institute, Kyoto University, Associate Professor, 大学院理科学研究科, 助教授 (10025421)
SHIMIZU Ichiko Graduate School of Science, University of Tokyo, Assistant, 大学院理科学研究科, 助手 (40211966)
MATSUURA Mitsuharu Graduate School of Science, University of Tokyo, Professor, 大学院理科学研究科, 教授 (00114645)
YAMASHITA Teruo Earthquake Research Institute, University of Tokyo, Professor, 地震研究所, 教授 (10114696)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,900,000 (Direct Cost: ¥7,900,000)
Fiscal Year 1997: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1996: ¥6,500,000 (Direct Cost: ¥6,500,000)
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| Keywords | Fault / Earthquake / Pseudotachylyte / Fault constitutive property / High velocity friction / Frictional melting / Earthquake initiating processes / Seismic fault motion / 摩擦熔融 |
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| Research Abstract |
Intrafault processes are far more dynamic than normally considered. The slip rate along a fault during seismic fault motion reaches about 1m/s or even faster and the total displacement along fault amounts to several meters for large earthquakes. Occasional occurrance of pseudotachylytes along exhumed faults indicates that frictional melting indeed occurs at least during some earthquakes. Thus, the frictional properties of faults at high velocities and under large displacements are quite significant to understand the earthquake initiating processes, but they have not been systematically studied. Conventional appearatuses are too limited in the amount of fault displacement to produce frictional melting and are unable to simulate thermally natural intrafault processes. Experiments using a high-velocity rotary friction apparatus, installed to Earthquake Research Insitute, University of Tokyo in 1990, has revealed that the effects of frictional heating on the mechanical properties of faults
… More
are larger than other effects such as slip rate by more than one order of magnitude. The main task of the present research project has been to design and build the second high velocity apparatus for studying high velocity frictional properties under hydrothermal conditions and to perform additional experiments using the first apparatus. The major results are as follows.
(1) A new rotary-shear high velocity friction apparatus was designed and built and this can produce slip rates ranging from 3 mm/yr up to almost 10 m/s, at ambient water pressures to 50 MPa, and at temperatures to 500 degrees Centigrade. Tests were successful and the machine will open ways of studying not only high velocity frictional properties of faults under hydrothermal conditions, but also frictional and wear properties of materials under high-temperature corrosive environments.
(2) Overall mechanical properties of simulated faults in dry gabbro have been revealed through experiments using the first high velocity machine.
(3) Two-stage model for the earthquake initiating processes has been proposed based on the dry high velocity experiments, and this may account for the origin of seismic quiescence. Less
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