title of the thesis - Department of Geology - Queen's University
title of the thesis - Department of Geology - Queen's University
title of the thesis - Department of Geology - Queen's University
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Axes for event clusters 1 and 2 are presented for comparison in Figures 3.18 and 3.19. T-axes for<br />
Cluster 1 events have similar trends but steeper dips, while B-axis trends vary in orientation from<br />
NNE-trending and with shallow plunges to near-vertical.<br />
3.3.1.3 Fault Plane Solution Discussion<br />
Event mechanisms do not show a direct correlation to mine-scale faults. Event mechanism types<br />
are distributed over <strong>the</strong> study area (Fig. 3.20) and do not cluster or align with individual faults.<br />
The distribution <strong>of</strong> event mechanism types thus does not allow <strong>the</strong> neokinematics <strong>of</strong> specific faults<br />
to be determined and does not suggest fault activity.<br />
Microseismic event mechanisms show consistency in P- and T-axis orientations, suggesting<br />
reactivation <strong>of</strong> preferentially oriented fractures. Lack <strong>of</strong> consistency in macroseismic event<br />
solutions suggests that failure does not localize along shear zones in <strong>the</strong> Creighton Deep. This<br />
inconsistency instead indicates more variation in <strong>the</strong> geometry <strong>of</strong> failure surfaces. Alternatives to<br />
fault-slip are proposed:<br />
<br />
Macroseismic events may embody <strong>the</strong> breaking <strong>of</strong> asperities between existing fractures or<br />
weak zones. This can occur along variably oriented pathways and in different faulting<br />
styles.<br />
<br />
Joints and preexisting fractures in <strong>the</strong> rock mass may interact to form a slip radius<br />
sufficiently large to accommodate large magnitude events.<br />
Coulson (1996) postulated that slip between <strong>the</strong> 6600 and 7200 Levels in Creighton Mine<br />
occurred along networked joint planes ra<strong>the</strong>r than on faults. Coulson (1996) concluded that<br />
seismicity in <strong>the</strong> Creighton Deep is related to <strong>the</strong> rock mass joint fabric and is <strong>the</strong> result <strong>of</strong><br />
mining-induced stresses.<br />
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