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

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3.2.1.6 Peak Acceleration Parameter, Velocity Parameter and Maximum Displacement<br />

Calculated motion parameters include peak acceleration, peak velocity and maximum<br />

displacement. The spatial distribution <strong>of</strong> stress parameters shows <strong>the</strong> same trends as <strong>the</strong> stress and<br />

source dimension parameters: low parameter values are observed to <strong>the</strong> south and sou<strong>the</strong>ast <strong>of</strong> <strong>the</strong><br />

excavation; while higher parameter values are found to <strong>the</strong> southwest <strong>of</strong> <strong>the</strong> excavation, and<br />

elevated values directly east <strong>of</strong> <strong>the</strong> excavation where blasting occurs.<br />

3.2.2 Spatial and Temporal Event Clustering<br />

Microseismic events tend to cluster spatially and temporally. Events that cluster in space and time<br />

can result from a localized increase in differential stress (Mendecki, 1997). Clusters <strong>of</strong><br />

microseismic events typically follow a large event, such as a rockburst or a blast.<br />

Spatial and temporal trends were studied in data surrounding <strong>the</strong> 7200, 7400 and 7530 levels.<br />

Levels below <strong>the</strong> 7530 Level were omitted from analysis since microseismic activity reflected<br />

development, making it difficult to distinguish between blast-induced and stress-induced events.<br />

Event frequency is observed to increase with depth, including <strong>the</strong> number <strong>of</strong> macroseismic events.<br />

Exceptionally high rates <strong>of</strong> seismicity on and below <strong>the</strong> 7680 Level reflect active level<br />

development in <strong>the</strong> Deep.<br />

Analysis is concentrated on events to <strong>the</strong> south <strong>of</strong> <strong>the</strong> 400 Orebody excavation (shown previously<br />

in Figure 2.5). This population has good sensor coverage, exhibits low location error and occurs<br />

away from blasts. Dense event clusters directly to <strong>the</strong> east and west <strong>of</strong> <strong>the</strong> excavation are<br />

attributed to production blasts from outward excavation (Fig. 3.6A). Events to <strong>the</strong> north <strong>of</strong> <strong>the</strong><br />

excavation are located outside <strong>the</strong> network, resulting in high location errors (Fig. 3.6A). Poorly<br />

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