NUCLEATION AND PROPAGATION PROCESSES OF STICK-SLIP FAILURE AND NORMAL STRESS DEPENDENCE OF THE PHYSICAL PARAMETERS OF DYNAMIC SLIP FAILURE

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概要

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• To understand earthquake failure processes in terms of physics, we have investigated stick-slip shear failure processes using a granite sample with a simulated fault which is large compared with the cohesive zone size. Nucleation preceding dynamically propagating rupture was found for stick-slip failure in a finite localized zone along the fault. In the nucleation zone over which the quasi-static slip motion took place there was no stress increase before the slip-weakening process. No significant difference in the critical displacement was found between the nucleation zone and the zone of dynamic rupture propagation; however, both breakdown stress drop and shear fracture energy were significantly smaller in the nucleation zone. The maximum slip velocity and acceleration were much lower in the nucleation zone than in the zone of dynamic rupture propagation. The maximum local slip velocity u_<max> and the maximum slip acceleration u_<max> for dynamic slip failure along the fault increased with increasing normal stress σ_n across the fault plane; u_<max> was quadratically related to σ_n, and u_<max> quartically to σ_n. The critical displacement u_c tended to increase as σ_n increased. These findings are consistent with an independent observation that the cutoff frequency f_<max> of the power spectral density of the slip acceleration-time record increases linearly as σ_n increases. f^2_<max> was proportional to u_<max>, and f_<max> increased with increasing breakdown stress drop, rupture velocity or u_<max> and with decreasing u_c. The maximum slip acceleration during slip failure along the fault is given by u_<max>=k_2u^2_<max>/u_c in which k_2 is a non-dimensional numerical constant, and k_2〓3 was obtained from the present data set. The cutoff frequency can be estimated from the relation f_<max>=4(1-ν)/πu_<max>/u_c in which ν is Poisson's ratio. Size-scale-dependent parameters such as u_<max> are scaled to the cohesive zone size or to the critical displancement, and hence the results obtained can be extended to actual earthquake source failure.

• 日本自然災害学会の論文

著者

• Kuwahara Yasuto

  Faculty Of Science Tohoku University

• OHNAKA Mitiyasu

  Earthquake Research Institute, University of Tokyo

• YAMAMOTO Kiyohiko

  Faculty of Science, Tohoku University

• Ohnaka Mitiyasu

  Earthquake Research Institute University Of Tokyo

• Yamamoto Kiyohiko

  Faculty Of Science Tohoku University

関連論文

• NUCLEATION AND PROPAGATION PROCESSES OF STICK-SLIP FAILURE AND NORMAL STRESS DEPENDENCE OF THE PHYSICAL PARAMETERS OF DYNAMIC SLIP FAILURE

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