2022 Fiscal Year Final Research Report
Sensitivity of earthquakes to stress perturbation: theory and experiment
| Project/Area Number |
19H01811
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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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| Review Section |
Basic Section 13010:Mathematical physics and fundamental theory of condensed matter physics-related
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 地震 / 潮汐 / 地震発生率 / 規模別頻度分布 |
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| Outline of Final Research Achievements |
Tidal response of earthquakes is studied based on the nucleation and rupture dynamics of some theoretical models. In particular, the effects of stress perturbation on the occurrence rate and the size-frequency distribution are discussed. It is found that the results are highly dependent on the assumed friction law. Assuming the rate- and state-dependent friction law, which has been confirmed by rock friction experiments, the seismicity increases exponentially with the Coulomb stress change, and the characteristic stress is proportional to the normal stress. On the other hand, in a simple friction law with static and dynamic friction, the seismicity increases linearly with the Coulomb stress change. The perturbation of the normal stress also has a large influence on the size-frequency distribution, and even a slight decrease in the normal stress is found to change the size-frequency distribution.
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| Free Research Field |
非平衡物理学
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| Academic Significance and Societal Importance of the Research Achievements |
地震の発生機構に関する科学的理解は、日本のみならず地震発生帯に位置する国々にとっての重要課題である。本研究は地震の発生機構解明に関する基礎研究として位置付けられる。本研究のテーマである、わずかな応力変化が地震発生率や規模別頻度分布に影響を及ぼす現象は防災・減災にとっても大きな意義を持っている。本研究の成果をさらに発展させることで、応力摂動への応答に関する観測データから断層に働く摩擦力の性質を（ある程度）拘束できるようになる。地震発生過程に関する謎の多くは断層に働く摩擦力が分からないことに起因しているので、ここから地震の発生機構に関する科学的理解がさらに進むことが期待される。
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