title of the thesis - Department of Geology - Queen's University

) Damage Zone
The rock mass in the Damage Zone has been progressively weakened by continued seismicity.
This area is subject to high stress and is a zone of fracture growth and localization. Rock
undergoing strain softening has slow rupture velocities and results in small stress releases (small
stress drops), low seismic moments as compared to failure, small energy releases (E o ) and small
apparent stresses (Mendecki, 1997).
Clusters 2 and 3 have seismic event parameters comparable to those expected in the Damage
Zone. The rock mass in the vicinity of clusters 2 and 3 has been progressively degraded by
seismic activity and is assigned to this zone. A series of rockbursts associated with unsupported
ground surrounding old ventilation infrastructure contributes to seismicity in Cluster 3 (Vale Inco,
pers. comm., 2009). This approximates post-peak conditions described by Coulson and Bawden
(2008).
c) Intact Zone
The Intact Zone is remote from mining and the stress influence of the excavation. This zone is
subject to background stresses and experiences low rates of seismic activity (the presence of
drifts, ramps etc. is not considered in this simplified model). Events occurring beyond the
nucleation zone have faster rupture velocities and are more energetic (Mendecki, 1997).
Cluster 1 exhibits high seismic parameter values, as expected for the Intact Zone. Sustained
seismicity (2000 through 2008) in this area corresponds to mining of the Plum Orebody (shown as
the 6100 Orebody in Figure 2.4) on upper mine levels. An increase in event density in Cluster 1
during the 2006-2007 time period corresponds to the onset of mining in the 461 Orebody (shown
in Figure 2.4), which was mined in stopes from the 7680 Level to the 7755 Sublevel.
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