2021 Fiscal Year Final Research Report
Seismic exploration of Earth's deep structure beneath storms using teleseismic body wave microseisms
| Project/Area Number |
17H02950
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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 |
Solid earth and planetary physics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
高木 涼太 東北大学, 理学研究科, 助教 (10735963)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Keywords | 地動の脈動 / 地球内部構造推定 |
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| Outline of Final Research Achievements |
In order to estimate the deep Earth structure, we proposed to treat teleseismic P-wave microseisms as spatially localized events with a long time duration. For this purpose, we analyzed Hi-net data in Japan from 2004 to 2020 and compiled the centroid single force catalog of P-wave microseisms in the frequency band of 0.1-0.25 Hz. The catalog values were quantitatively compared with ocean wave action models and found to be consistent in most regions.
We attempted to detect P-s converted waves in the transition layer just below the Japanese Islands using the catalog. First, we estimated the source time function of incident P waves using array analysis and removed its effect from the horizontal records. As a result, we succeeded in detecting P-s waves at the 410 km and 660 km discontinuities below the stations.
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| Free Research Field |
地震学
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| Academic Significance and Societal Importance of the Research Achievements |
地震学的手法を用いて地球深部構造の推定する場合には、通常大地震のデータを解析に用いる。本研究課題では、代わりに海洋波浪起源の地震波による探査を提案している。これまでとは独立な情報を用いることによって、地球の深部構造を調べる新たな眼を手に入れるための第一歩といえる研究課題である。また、提案している地球内部構造探査のためには海洋波浪の理解が不可欠である。長期的には、海洋物理学と地震学の橋渡し的な役割も担うと考えている。
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