The evaluation of failure components using the seismic moment tensor inversion

The inversion of the seismic moment tensor allows for a characterization of failure components. An original technique is proposed, using time domain equivalent low-frequency spectral displacements with first arrival polarities attached. The identification of each particular wave-type is based on wave energy functions and polarization criteria. The technique is applied to microseisemic events recorded at the Kidd mine, Ontario, with their underground microseismic array. This array includes 20 uniaxial and 8 triaxial accelerometers and monitors a volume of about 300 x 300 x 400 in. Inversions are carried out for pure shear, complex shear, and a general mechanism, including both shear and tensile components. The results show that distinct mechanisms are responsible for the stress transfer effects observed in different regions of the mine. Events that occur within a pillar on the 4,700 Level have positive tensile components, whereas events that occur outside the orebody are characterized as pure-shear failures, similar to those induced in a fractured rockmass on the 5,600 Level.