There is a strong indication that mine seismicity in open pit environments is generally caused by non-shear mechanism. This seismic mechanism is poorly understood and needs further investigation as it has important implications with respect to the modelling of rock failure, rock mass behaviour and the design of long-term large rock slopes. Source models assuming double couple shear, often used in mine seismology, may not be applicable to all the microseismic events recorded in the open pit environment.
The biaxial loading state occurring closer to the slope face is conducive to the generation of larger fractures. The largest fractures are expected to occur behind the blast damage zone. Further work is required to confirm this.
Several practical difficulties still exist that prevent the technology being implemented as a routine monitoring method. These pertain to cost-effective access and useful lifespan of the system, as well as processing and interpretation of the data.
It appears that, generally, chosen sensor arrays are too sparse to provide meaningful microseismic data on the development of the failure mechanisms. Guidelines for the conceptual design of seismic systems for open pit hard rock applications are provided in the MERIWA project report M366.