| Project/Area Number |
11680465
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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 |
Natural disaster science
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| Research Institution | Tohoku University |
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Principal Investigator |
MATSUZAWA Toru Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (20190449)
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| Co-Investigator(Kenkyū-buntansha) |
OKADA Tomomi Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (30281968)
HINO Ryota Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (00241521)
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| Project Period (FY) |
1999 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
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| Keywords | small repeating earthquakes / plate boundary / characteristic earthquakes / similar earthquakes / interplate coupling / quasi-static slip / aseismic slip / asperity / カップリング / 非地震生すべり |
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| Research Abstract |
Numerical simulations based on the recent frictional constitutive laws indicate that plate boundaries slip quasi-statically in the inter-seismic period especially around the edges of coupling areas. The purpose of this study was to detect the quasi-static slips and investigate the nature.
The study revealed that many small repeating earthquakes were occurring on the plate boundary east off the northeastern Japan arc. Using the repeating earthquakes we succeeded in estimating the spatio-temporal distribution of quasi-static slips on the plate boundary. The results indicate that the boundary around the western (deeper) edges of coupling areas slips quasi-statically with a speed of almost the same as the interplate convergence rate. We also revealed that large afterslips had followed the 1994 Far-off-Sanriku earthquake even in the regions close to the Japan trench, which was not detected by the GPS data analyses. Moreover, we found that all the interplate events of M6 or lager had been followed by large afterslips.
We also investigated the relation between the structure and seismicity around the trench. We have proposed a model that the property of the oceanic layer 2 strongly affects the seismicity. The slip behavior should be affected by the rigidity as well as the frictional parameters on the boundary. Thus, it is very important for understanding the slip property to investigate the detailed structure on and around the boundary.
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