| Project/Area Number |
17540394
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KATO Naoyuki The University of Tokyo, Earthquake Research Institute, Associate Professor, 地震研究所, 助教授 (60224523)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAZAKI Shin'ichi The University of Tokyo, Earthquake Research Institute, Research Associate, 地震研究所, 助手 (00334285)
MATSUZAWA Toru Tohoku University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (20190449)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | constitutive friction law / numerical simulation / earthquake cycle / interplate earthquake / postseismic sliding / repeating earthquakes |
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| Research Abstract |
(1) Numerical simulation about interaction between aseismic sliding and earthquakes. We performed numerical simulations of sliding behavior on plate interfaces using laboratory-derived rate- and state-dependent friction laws to understand the effects of aseismic sliding on earthquake occurrence. Considering recurrence rupture of a large asperity, where velocity-weakening friction was assumed, we modeled postseismic sliding propagating slowly outward in velocity-strengthening region around the asperity. From the simulations, we found the property of propagating postseismic sliding, such as the propagation speed, depends on friction parameters, and the propagating postseismic sliding may trigger rupture at small asperities, causing time dependent expansion of aftershock areas. The results indicate that the observations about space-time evolution of postseismic sliding from geodetic data and about time dependent aftershock areas may be useful for estimating friction parameters. Furthermor
… More
e, the simulations indicate that perturbation in sliding velocity due to rupture of a large asperity significantly affects the characteristics of rupture of small asperities because of time and rate dependence of frictional characteristics. This effect must be taken into consideration in estimating sliding velocity from recurrence pattern of small repeating earthquakes. (2) Analysis of geodetic and seismic data. The spatio-temporal evolution of aseismic sliding on the plate interface below the hypothetical source area of the Tokai earthquake was estimated from GPS data. We obtained the relations between shear stress and slip and between shear stress and slip rate, and velocity-weakening frictional property was estimated from the relations. This is consistent with a model for slow earthquakes on the basis of the rate- and state-dependent friction. The spatio-temporal evolution of aseismic sliding on the plate interface along the Japan trench, northeastern Japan, was estimated from the analysis of small repeating earthquakes. In order to estimate sliding velocities from the data of small repeating earthquakes, the relation between coseismic slip and magnitude is required. The empirical relation for small repeating earthquake is significantly different from that has been used for usual earthquakes, in which stress drop is constant. On the basis of fracture mechanics of an asperity, a theoretical explanation for the empirical scaling relation for the small repeating earthquakes was obtained. Less
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