| Co-Investigator(Kenkyū-buntansha) |
SAMMONDS Peter R. Research Fellow, University College London, 地球物理学部, リサーチフェロー
GLOVER Paul W.J. Research Fellow, University College London, 地球物理学部, リサーチフェロー
WATANABE Kimio JSPS Reserch Fellow, Tohoku University, 工学部, 学振特別研究員
TAKAYASU Misako JSPS Rsearch Fellow, Tohoku University, 工学部, 学振特別研究員
SATO Kazushi Research Assistant, Tohoku University, 工学部, 助手 (80235324)
TSUCHIYA Norimasa Research Assistant, Tohoku University, 工学部, 助手 (40207410)
HASHIDA Toshiyuki Associate Professor, Tohoku University, 工学部, 助教授 (40180814)
TAKAYASU Hideki Professor, Tohoku University, 大学院情報科学研究科, 教授 (00183062)
HAYASHI Kazuo Professor, Tohoku University, 流体科学研究所, 教授 (30111256)
MATSUKI Kouji Professor, Tohoku University, 工学部, 教授 (10108475)
MEREDITH Philip G. Reader, University College London, 地球物理学部, リーダー
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| Research Abstract |
The observed fractal nature of both fault length distributions and earthquake magnitude-frequency distribution suggests that there may be a relationship between the structure of active fault systems and the resulting seismicity. Here, we present the first experimental evidence for a correlation between the fractal dimension of fracture length distribution D and acoustic emission (AE) b-value based on a series of tensile fracture mechanics tests on crystalline rock, carried out in different environmental conditions, both air-dry and water-saturated at ambient temperature and pressure. The constant stress intensity, K_I, and quantitative analyses of the resulting fracture patterns were carried out on the same specimens. It is found that AE b-values, ranging from 1.0 to 2.3, correlate negatively with normalized stress intensity K_I/K_<IC>, where K_<IC> is the fracture toughness of the specimen. The fractal dimension of fracture length distribution D, ranges from 1.0 to 1.7. Fluid presence has a first-order influence on both the AE and structure produced in these experiments. For experiments at low stress intensity or high fluid content, the activation of the stress corrosion mechanism for K_I < K_<IC> leads to a greater relative proportion both of small cracks and of low amplitude acoustic emissions, reflected in higher values of D and b. The fractal dimension D is found to correlate positively with the AE b-value.
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