2019 Fiscal Year Final Research Report
Seismicity as Complex Phenomenon with Catastrophes: Correlation, Dynamics and Network Representation
| Project/Area Number |
16K05484
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Mathematical physics/Fundamental condensed matter physics
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| Research Institution | Nihon University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
阿部 純義 三重大学, 工学研究科, 教授 (70184215)
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Keywords | 地震活動 / カタストロフ / 複雑系科学 / 火山性地震 / 時空間相関 / Markov過程 / 複雑ネットワーク / 異常拡散 |
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| Outline of Final Research Achievements |
From the view point of science of complexity, we studied volcanic seismicity. We showed that the growth of the seismic region in time is subdiffusive at both Mt Etna in Sicily and Eyjafjallajokull in Iceland. Although the volcanic seismicity always occurs before eruption, eruption may not necessarily take place even if the seismicity occurs. We found that the complex earthquake networks constructed from the seismic datasets taken in Iceland and Japan exhibit a common structural change prior to their large-scale eruption. The Gutenberg-Richter law shows that the distribution of earthquake energy asymptotically decays as a power law with no characteristic scale. Although the power law like this also can been seen widely in the complex systems, the similarity in the distribution does not directly tell us if the process underling these intermittent phenomena are memoryless (i.e., Markovian ) or not. We constructed a new simple method for quantitatively evaluating (non-)Markovianity.
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| Free Research Field |
理論物理学
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| Academic Significance and Societal Importance of the Research Achievements |
地震活動に対する理解をカタストロフ複雑系現象という新たな視点から深めることを目的とする。前半は、火山性地震の震源が時間と共に広がる様子が、水にたらしたインクの広がり方とは異なる異常拡散であることを明らかにした。また、火山性地震は必ずしも噴火に至る予兆現象と見なすことはできないが、噴火に至る場合のみ地震の複雑ネットワークに特異的な振る舞いが現れることを明らかにした。地震活動には、他の多くの複雑系と共通のいくつかのベキ法則が存在する。後半は、ベキ則を示す複雑系のダイナミクスが記憶を引きずるか否かを判定する数学的な理論を展開した。この成果は、系の未知のダイナミクスの理解に新たな光をあてるものとなる。
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