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North Fork Valley Seismic Network - Second Quarter 2010 <br />area (Figure 1). Each station consists of three - component accelerometers. The locations of <br />seismographic stations operating during the 2010 second quarter are presented in Table 1 and <br />shown on Figure 1. <br />Table 1. Seismograph Stations of the North Fork Valley Seismic Network <br />Station <br />Latitude <br />(degrees) <br />Longitude <br />(degrees) <br />Elevation <br />(ft) [m] <br />Station <br />Correction <br />(sec) <br />Station Name <br />Owner <br />BWK <br />38.928 <br />- 107.537 <br />6701 [2042] <br />-0.139 <br />Bo«ie King Mine <br />BRL <br />FGH <br />3 8.94 8 <br />- 107.536 <br />7201 [2195] <br />- 0.087 <br />Freeman Gulch Hubbard <br />BRL <br />LLM <br />38.857 <br />- 107.461 <br />8240 [2512] <br />0.042 <br />Lion Mesa <br />MCC <br />MCD <br />38.881 <br />- 107.474 <br />7274 [2217] <br />-0.079 <br />Minnesota Creek Dam <br />MCC <br />MFB <br />38.956 <br />- 107.559 <br />7924 [2415] <br />-0.002 <br />Middle Forest Boundary <br />BRL <br />NOB <br />38.973 <br />- 107.542 <br />7644 [2330] <br />0.109 <br />Bowie King Mine <br />BRL <br />OXM <br />38.961 <br />- 107.493 <br />8130 [2139] <br />0.030 <br />Oxbow Mine <br />NIOSH <br />SPG <br />38.872 <br />- 107.425 <br />8174 [2491] <br />0.033 <br />South of Poison Gulch <br />MCC <br />SEF <br />38.874 <br />- 107.390 <br />8667 [2642] <br />0.101 <br />South of East Flatiron <br />MCC <br />TCR <br />38.982 <br />- 107.564 <br />848 <br />0.075 <br />Terror Creek Dam <br />BRL <br />WFW <br />38.901 <br />- 107.424 <br />84 <br />0.068 <br />West Flatiron West <br />MCC <br />WTM <br />38.941 <br />- 107.591 <br />7954 [2424] <br />0.002 <br />West Tower Mountain <br />BRL <br />The development of NFVSN is described in previous reports. Real -time processing utilizes <br />modules from the Earthworm software suite developed by the U.S. Geological Survey (USGS) <br />in Menlo Park, California (Johnson et al., 1995). The program detects, automatically locates, and <br />saves event data for triggered events. The network is divided into two sub -nets (each with six - <br />stations), one in each of the two main mining areas (Figure 1). <br />DATA PROCESSING <br />Identification of Events <br />Events are regarded as seismic in origin and logged by the Earthworm triggering system if they <br />appear on five or more stations with significant amplitude, impulsive onset and appropriate time <br />differences between stations. Triggering occurs within the two sub -nets (six stations in each) so <br />that important events are not missed. Earthworm also provides automatic locations for events <br />that have sufficient arrival time picks. During the second quarter, Earthworm detected and <br />UM WAX_WCFS \PROJECTS \WEST ELK -MTN COAL \2010 Q2 \Q2_2010_ MCC. DOC\31 -AUG-1 0\\OAK 2 <br />