| The goal of this thesis was to identify accurate, useful and non-labor-intensive methods of estimating seismic attenuation in underground mining environments, and to relate the attenuation information to rock mass characteristics as determined from geomechanical data. Computer programs were designed specifically for each of four methods investigated. The results obtained from the analyses were unique to the case study sites and indicated important attenuation characteristics at microseismic frequencies.;The initial study at the Underground Research Laboratory (URL), in Pinawa, Manitoba, was designed to test the feasibility of using the Spectral Ratio method in situ at an underground mine. While the study was successful in terms of the accuracy of the results obtained, it identified the difficulty that would be faced in utilizing Spectral Ratio analysis in an active underground mining environment.;The second study, at the Strathcona Mine, in Sudbury, Ontario, was meant to investigate the application of attenuation analysis to active mining environments using passively-acquired seismicity. While the Spectral Ratio method was not employed, modified Spectral Decay and Coda-Q methods were used along with the Multiple Lapse Time Window Analysis. At the Strathcona site, the Spectral Decay method proved to work reasonably well, and it was thought that this method should be appropriate for use in underground mines. However, this success later proved to be due to the painstaking effort in identifying shear-failure seismicity, and the fact that only a single station was used in the analysis.;The final site, Creighton Mine in Sudbury, Ontario, served a two-fold purpose. The first was to use the previously developed methods for a multiple-station analysis and, the second, to investigate the frequency dependence of attenuation by using data from the microseismic and Strong Ground Motion (SGM) monitoring systems. While the first goal was merely an extension of the analysis carried out at the Strathcona site, the second was unique in its approach. It is atypical that a volume of rock is monitored by seismic systems "tuned" to completely different frequencies. However, the SGM and microseismic monitoring systems measure seismicity at frequencies between 10-800 Hz and 250-3500 Hz, respectively. Hence, the quality factors estimated with the two systems for the identical rock mass indicated the frequency dependence of the attenuative properties of the rock over a broad bandwidth. Furthermore, when the results from the URL and Strathcona analyses were included, the analysis of the frequency dependence of attenuation was extended to an even greater bandwidth.;The conclusions of this research were that each of the methods investigated has merit and could be further exploited to develop accurate two- and three-dimensional images of quality factors in underground mines. The techniques were not original in their methodology, rather it was the application and adaptation of the techniques that was significant, as would be their further development. (Abstract shortened by UMI.)... |
