Accerelation of the fracture growth in laboratory

• We analyzed temporal changes in the quality factor, velocity, and amplitude of P waves transmitting through a fracturing Westerly granite sample under tri-axial compressive conditions to monitor the heterogeneous condition in the sample. The first wave amplitude clearly decreased rapidly after the occurrence of the peak stress. These results indicate the acceleration of the crack generation and connection in the sample to form the rapture plane.
  
  
  (a) Temporal changes in the quality factor, (b) P-wave velocity, (c) the first wave amplitude during tri-axial compression test (after Yoshimitsu et al., 2011). (c’) The enlarged time series of (c).
  
  See Yoshimitsu et al. (2009) and Yoshimitsu and Kawakata (2011) for a detailed description.
  Broadband P waves transmitting through fracturing Westerly granite before and after the peak stress under a triaxial compressive condition
  
  Temporal Changes in the Q of Broadband P Waves Transmitting through a Fracturing Westerly Granite Sample under Triaxial Compressive Conditions