| Project/Area Number |
08640527
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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 |
固体地球物理学
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
OKAMOTO Taro Tokyo Institute of Technology, Guraduate School of Science and Engineering, Research Assistant, 大学院・理工学研究科, 助手 (40270920)
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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 |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | seismic waves / source process / moment tensor / 沈み込み帯 / 差分法 / 地震波理論 |
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| Research Abstract |
(1)Far field body wave code
A new, very effective 2.5D plane wave propagation FDM code based on Takenaka & Kennet (1996) algorithm has been developed by co-working with them (Takenaka and Kennett), It is much faster than the previous one (more than 10 times faster). We expect it is applied to various problems including our own research.
2)Near field complete seismic waveform code
We have verified the accuracy for the fluid-solid boundaries for finite-difference method and have found a proper grid arrangement to improve the accuracy. The resultant code generates waveforms that matches well with the observed waveforms for the seismo-acoustic environment.
3)Moment tensor inversion by using near-field full waveforms
We have developed a method based on the reciprocal theorem. This method can generate Green's functions for a station and various source locations in a single calculation. It is considered that this approach will become one of the standard method. We tested the fundamental aspects of
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this method by applying our code for a shallow earthquake at Japan Trench and obtained a very reasonable inversion result. This ensures the applicability of the approach.
4)Far fried body waveform analysis code
We have developed two codes : one is to determine the source mechanism and the source position and the other is to determine the distribution of the moment release on a fault, In the latter code, we have formulated a non-linear inversion procedure to avoid a negative moment. We have applied our new method to the analysis of 1992 Nicaraguan Tsunami earthquake for which a very shallow moment release is suggested by tsunami waveform analysis. Our result based on the seismic waveforms suggest a relatively deep moment release.
5)Parallel code
We have used the standard mechanism for inter-process communications on UNIX OS to implement a parallel functionality in our near-field waveform code. For a dual processor calculation, we observed a 1.5 times acceralation against a single processor calculation. Our code has not achieved the optimum parallelism and further study will be required. Less
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