Source parameter scaling relations are examined for microseismic events (−2.4 ≤ M ≤ −0.3) occurring within highly and moderately stressed and fractured rock masses at Strathcona mine, Sudbury, Canada. Insight into scaling is provided by waveform complexities, calculated rupture velocities, and maximum shear stresses based on in situ and numerical modelling data. The importance of normal stress on the failure process is also considered. Our results show that a strong dependence exists between stress release and seismic moment. An observed positive scaling in excess stress release (Δσ/2 − σ a ) is consistent with the concept of overshoot. Rupture velocities ranging from 0.2 to 0.5β and waveform complexities less than 1.5 suggested that overshoot was related to healing behind a slowly advancing rupture front. Scaling in seismic efficiency paralleled that in apparent stress, implying that seismic stress release estimates arc quasi-independent of the maximum shear stress. High levels of normal stress further supported the importance of high resisting stress in the observed overshoot behaviour and its role in the failure process.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Effects of Rupture Complexity and Stress Regime on Scaling Relations of Induced Microseismic Events
Theodore I. Urbancic
- Birkhäuser Basel