The Role of Ground Truth in Improved Identification of Mining Explosion Signals Utilization of Calibration Explosions and Acoustic Signals

The characterization and identification of small magnitude seismic sources using regional observations involves the analysis of signals from natural and man made sources. Proper event classification will depend upon the appropriate assessment of source and propagation path effects. Our work is intended to investigate supplementary procedures and data sets that can improve source characterization procedures. Several approaches to improved source identification procedures have been investigated including: (1) Execution of contained calibration explosions; (2) Utilization of regional array data for improved separation of source and propagation path effects; (3) Development of in-mine ground truth through mine records or on site instrumentation; (4) Combining seismic and infrasound data for source characterization. A series of single-fired calibration shots were detonated in a mine in NE Wyoming for the purpose of developing source scaling relations and comparison to typical delay-fired explosions. Regional data from these explosions are consistent with a simple Mueller-Murphy source model. The variation in seismograms across regional arrays is used to contrast local site effects with source and regional propagation contributions. The three IMS arrays in the western US TXAR, PDAR and NVARwere used in the study. TXAR with its homogeneous geology shows the least variability and NVAR with instruments in seven different rock types shows the greatest variation in both amplitudes and wave shapes. Ground truth from controlled mining explosions can be obtained from typical blasting records maintained by the mines or more directly from close-in seismic and acoustic observations from within the mine. Mines in the Iron Range (IR) of Minnesota, the Powder River Basin (PRB) in Wyoming, and the Porphyry Copper District (PCD) of east central Arizona and south west New Mexico were used in gathering ground truth ranging from mine records (IR) to in-mine monitoring (PRB and PCD). The contribution of this information to regional monitoring is compared and contrasted. The focus of this paper will be on the in-mine ground truth developed in the PCD and applied to to regional seismic and infrasonic signals. Seismic and infrasonic signals both in-mine and at regional distances will be used in characterizing the source and propagation path effects.