2007 Fiscal Year Final Research Report Summary
Mechanisms of Tsunami earthquakes
| Project/Area Number |
18540414
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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 | Nagoya University (2007)
The University of Tokyo (2006) |
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Principal Investigator |
YAMANAKA Yoshiko Nagoya University, Graduate School of Environmental Studies, 准教授 (30262083)
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| Project Period (FY) |
2006 – 2007
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| Keywords | earthquake / tsunami / asperity |
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| Research Abstract |
In order to clarify of characteristic of tsunami earthquakes, the detail source processes of tsunami earthquakes were investigated. The reported tsunami earthquakes are the following earthquakes. 1975/06/10 Kurile (M7.0),1992/09/02 Nicaragua (M7.2),1994/06/02 Java (M7.2), 1996/02/21 Peru (M7.5). We analyzed the source processes of theses tsunami earthquakes.
The characteristics of tsunami earthquakes obtained in this study are as follows:
(1) If the rigidity is uniform, the amount of slip in the source region is small.
(2) The source region is larger than an ordinary earthquake.
(3) It has occurred in the shallow place from the trench.
(4) Rupture propagation velocity is not slow.
If the amount of moment release is small and rigidity near the trench is small, displacement is large and big tsunami increased.
On the other hand, subducting seamounts are thought to increase the normal stress between subducting and overriding plates and interplate coupling is weak, then repeating earthquakes of magnitude M~7 was occurred. The rupture propagation of the 1982 Ibaraki-oki earthquake imply that a large rupture area with small slip occurred in front of the seamount. The pattern of rupture was similar to tsunami earthquake.
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