Stress State Mapping Using Seismic Stress Inversion: Application to Kidd Mine
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This study investigates the applicability of seismic stress inversion in a mining environment with active geological structure, in order to map spatiotemporal stress states. First Motion Stress Inversion (MOTSI) (Abers, 2001) software is utilized, whereby this research outlines methods to establish spatiotemporal domains, determine inversion reliability and sensitivity, and explore the applicability and limitations of detecting stress state changes through seismic stress inversion. The application of spatiotemporal discretization to the methodology allows domains to be representative of pseudo-homogeneous stress states, to increase the reliability and resolution of mapped stresses. Geological structures are established as discrete boundaries of inversion domains, and were found to produce unique stress tensors representative of homogeneous stress states that differed from the stress states in adjacent domains. High seismic event frequency is established as a bound between temporal domains and stricter filters produce more reliable inversions. Stress tensors produced through the inversion method indicate an evolution of the stress path over time. Stress states only influenced by mining are gradual and smooth, whereas in the case of fault-slip, the evolution appears to display sharp changes at the time of the events. A significant limitation of this method is data sparsity. This is directly related to the number of filters applied to the dataset, thus a balance between filter strictness and database size must be considered. This work demonstrates the weak and brittle behaviour of the faults and that interconnected geological structure is significant in the seismic expression of the failure mechanism and can be captured through the inversion method. Through more research, the implementation of this method in real-time may bring insight as to which spatial domains or structures are at risk of fault slip, in addition to mapping the stress state. Overall, through an improved understanding of the stress state adjacent to weak structures, it is expected that seismic stress inversion will lead to greater reliability of stability analysis, consequently improving the design process for deep mines.