Fig. 7.

Fluctuation of b-value with volumetric strain rate ${\dot{\epsilon }}_v$; colour indicates time during the test. The volumetric strain rate was linearly interpolated to the b-value time stamps. The yellow triangle marks the beginning of the second b-value decrease as observed in Fig. 3(b). An inverse correlation between the b-value and ${\dot{\epsilon }}_v$ can be observed towards the end of the test.