Laserfiche WebLink
INTRODUCTION <br />This report is prepared by David Butler, Senior Geophysicist, Zonge Geosciences, Inc., Lakewood, <br />Colorado, in partial fulfillment of a commitment by Bowie Resources, Limited (BRL) to monitor <br />seismicity (including the microseismic activity near longwall mining activity) in the North Fork <br />Valley just east of Paonia, Colorado. This commitment is to the Colorado Division of Natural <br />Resources, Division of Reclamation, Mining and Safety. <br />The area encompassed extends east-west from Coal Creek Mesa to West Tower Mountain and <br />north-south from Terror Creek Reservoir to Lion Mesa (see Figure 1). The area includes Bowie <br />No. 2 Mine, property of Bowie Resources, LLC (BRL). Seismicity from Elk Creek Mine owned by <br />Oxbow Mining, Inc. is also recorded. <br />This report contains preliminary analyses of data collected in the second quarter of 2007, i.e. from <br />April to June, 2007. Stations in the network operated previous to this quarter, but this report <br />contains only information about the second quarter of 2007. Some seismological aspects of the <br />analysis are not yet completed. The velocity model, aground-motion attenuation model, station <br />delay times and network magnitude definitions are under construction. Further evolution of these <br />parameters and models will lead to refinement in the calculated event location coordinates and <br />magnitude estimations; however, the basic record of the seismic activity will remain unchanged. <br />This report focuses on seismologic conclusions completed during the analysis period. <br />The seismic monitoring program was designed to monitor seismicity levels, provide locations for <br />local events, measure ground motion quantitatively, and to determine focal mechanisms when <br />feasible. The ultimate objective of the program is to establish the ground motion regime that <br />structures within and near the network are and will be subject to during mining. <br />OPERATIONS <br />Station Locations and Descriptions <br />A multi-station seismic array (10 stations) was installed by a cooperative effort of MCC and BRL <br />and the Spokane Research Laboratory of NIOSH/CDC (National Institute for Occupational Safety <br />and Health/Centers for Disease Control and Prevention). Station locations were determined by <br />consideration of access, permission of landowners, specific array geometry, radio line-of--sight to <br />the common recording site (the Paonia Airport) or a repeater station and uniform coverage of the <br />target area (see Figure 1). <br />The location of stations presently operating are shown on Figure 1 and corresponding station <br />coordinates are listed in Table 1. The delay times shown are discussed below. <br />• <br />