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2022 Fiscal Year Final Research Report

n situ observation of fracture propagation of rocks and fault damage by synchrotron ultra fast X ray imaging

Research Project

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Project/Area Number 20H02002
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 17040:Solid earth sciences-related
Research InstitutionTohoku University

Principal Investigator

Nagahama Hiroyuki  東北大学, 理学研究科, 教授 (60237550)

Co-Investigator(Kenkyū-buntansha) 河野 義生  愛媛大学, 地球深部ダイナミクス研究センター, 准教授 (20452683)
武藤 潤  東北大学, 理学研究科, 教授 (40545787)
丹下 慶範  公益財団法人高輝度光科学研究センター, 回折・散乱推進室, 主幹研究員 (70543164)
Project Period (FY) 2020-04-01 – 2023-03-31
Keywords粉砕岩 / 断層破砕帯 / フラクタル / 衝突実験 / 断層破壊電波
Outline of Final Research Achievements

In order to elucidate the mechanism of rock pulverization formed during earthquake rupture propagation, we constructed an impact experimental rigusing the Split Hopkinson Pressure Bar method. We controlled the collision speed of the impact bar on samples of granite, novaculite from Arkansas, and Macore (machinable ceramics often used in previous studies), generating a very high strain rate exceeding 1000/s. As a result of the experiments, we clarified that the pattern of fracturing and crack propagation varies among each rock type, and that the grain size distribution of the pulverized samples exhibits a fractal size distribution similar to that has been reported from natural fault zones. This research presents a quantitative evaluation method for energy dissipation due to rock pulverization during earthquakes, and may have a significant impact on future studies of dynamic fault pulverization.

Free Research Field

固体地球科学

Academic Significance and Societal Importance of the Research Achievements

本研究では、地震時に断層周辺で発生する高いひずみ速度を再現できる衝突実験から、天然断層の粉砕度に近い高いフラクタル次元が得られた。また、実験による力学計測から動的粉砕時の破壊エネルギーの評価が可能であり、両者を結びつけることで断層周辺での岩石粉砕によるエネルギー散逸を定量的に把握することが可能となる。本研究により、破壊エネルギーの上限値を実験的に明らかにすることができれば、断層破壊の停止をエネルギーの観点から評価することのできる現実に近い地震破壊シミュレーション構築に貢献するだろう。

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Published: 2024-01-30  

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