Ground-Motion Recording and Analysis of Mining-Induced Seismicity in the Trail Mountain Area, Emery County, Utah

TABLE OF CONTENTS

TITLE PAGE

DISCLAIMER

EXECUTIVE SUMMARY

ACKNOWLEDGMENTS

1. INTRODUCTION

2. SEISMIC ARRAY DESIGN

3. DATA ACQUISITION, PROCESSING, AND ANALYSIS

4. OBSERVED MICROSEISMICITY

5. REFERENCES

LIST OF TABLES

Table 2-1	Field Project Timeline
Table 3-1	Data-Acquisition Scheme for Trail Mountain Seismic Array
Table 3-2	Seismic Events Recorded on Independently Triggered Stations &endash; October 3, 2000 - April 30, 2001
Table 3-3	Statistics for Hypocentral Location Error
Table 4-1	List of all Located Events in the TM Extended Study Area with Focal Depths = 2.5 km

LIST OF FIGURES

Figure 1-1	Location map of the Trail Mountain study area.
Figure 1-2	Oblique aerial view to ENE looking across Joes Valley Reservoir and graben toward the steep western flank of Trail Mountain.
Figure 1-3	Oblique aerial view to NW looking toward the steep southern and eastern flanks of Trail Mountain.
Figure 1-4	Seismicity map of the Utah region, 1978-2000, showing the location and setting of the Wasatch Plateau-Book Cliffs coal mining region.
Figure 1-5	Epicenter map of all seismic events located by the University of Utah regional seismic network in the Wasatch Plateau-Book Cliffs coal mining region from January 1, 1978, through June 30, 2000.
Figure 2-1	Map showing the distribution of eight triaxial accelerographs installed above, within, and surrounding the Trail Mountain Mine for ground-motion measurements.
Figure 2-2	Map of Trail Mountain seismic array.
Figure 2-3	Map showing stations of the University of Utah regional seismic network in the vicinity of the Trail Mountain study area.
Figure 2-4	Map of Trail Mountain showing details of the 1st and 2nd Right longwall panels-including timing of active mining, depth of cover, and areas of the two panels ultimately mined or left unmined.
Figure 3-1	Example webicorder images from stations TS2 and TS3 for a 24-hour period.
Figure 3-2	Scatter plots showing the distribution of 1,202 ground-motion measurements made at stations TB1, TB2, and TB3 in peak ground acceleration-distance space and corresponding magnitude-distance space.
Figure 3-3	Epicenter map of 49 seismic events selected as candidates for the USGS to consider for special analysis.
Figure 3-4	Epicenter map of 246 seismic events belonging to the UUSS refined data set and located within the local study area.
Figure 4-1	Histogram of the number of located earthquakes per day in the Trail Mountain earthquake catalog (October 3, 2000-April 30, 2001).
Figure 4-2	Histogram of 1,913 earthquakes in the Trail Mountain earthquake catalog (October 3, 2000 -April, 30, 2001) showing distribution by time of day.
Figure 4-3	Histogram of magnitude distribution for 1,913 events in the Trail Mountain earthquake catalog (October 3, 2000-April 30, 2001).
Figure 4-4	Plots of magnitude versus time from continuous monitoring of seismicity in the Trail Mountain local study area during October 2000 through April 2001 and January 1999 through December 2001.
Figure 4-5	Epicenter map of entire Trail Mountain earthquake catalog (extended study area).
Figure 4-6	Epicenter map of better-located seismic events (Quality A, B, C) within the local study area.
Figure 4-7	Epicenter maps of better-located earthquakes (Quality A, B, C) in the Trail Mountain Mine area for six consecutive time periods between October 2000 and April 2001 corresponding to periods of non-mining and active longwall mining.
Figure 4-8	Focal-depth histograms for the Trail Mountain earthquake catalog (October 3, 2000-April 30, 2001) and for earthquakes in the local study area with well-constrained depths < 2.5 km.
Figure 4-9	Epicenter map of extended study area showing locations of 24 earthquakes located with focal depth ( 2.5 km and 43 earthquakes recorded with at least one compressional first motion.

APPENDICES

Appendix A	Specifications and Calibration Data for Instrumentation Used in the Trail Mountain Study
Appendix B	Seismic Velocity Model for the Trail Mountain Study Area - by James C. Pechmann, Walter J. Arabasz, Kristine L. Pankow and Matthew E. Jensen
	Figures B-1 to B-4
Appendix C	Tabulation of Ground-Motion Data Delivered to USGS for Detailed Analysis
Appendix D	List of All Located Seismic Events in the Trail Mountain Local Study Area, October 3, 2000-April 30, 2001
Appendix E	Constraints on Locations of Mining Seismicity in the Trail Mountain Area - by Kristine L. Pankow, Matthew E. Jensen and James C. Pechmann
	Figures E-1 to E-10
Appendix F	Trail Mountain Project-Mining Engineering Considerations for Assessing Maximum Magnitude for Seismic Events - by Michael K. McCarter, with contributions from Jefferson D. McKenzie
	Figures F-1 to F-10

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