STATE-BY-STATE LIST OF MINING REGIONS

Significant sources of seismic events that are listed in "Routine Mining Seismicity in the United States," its predecessor "Probable Mining Explosions in the United States," or in earthquake catalogs of the USGS/NEIC.

Sources are identified by names of nearby communities.

ALABAMA

Bessemer -- Longwall mining of coal is conducted in several large underground mines west of Bessemer (Fiscor, 2000). The mining-induced events from this region that are large enough to be detected by the USGS/NEIC automatic event-detection algorithm are also large enough to affect earthquake hazard assessments; they are therefore listed in earthquake catalogs of the USGS/NEIC. Catalogs of routine mining seismicity do not yet contain events from this mining region. The largest suspected mining-induced event from this region that is listed in earthquake catalogs of the USGS/NEIC for 1973 -- March 2000 had MB = 4.8; the largest mbLg recorded for a mining-induced event from this region is 4.0 (see Mining-induced events in the earthquake catalogs of the USGS/NEIC).

ALASKA

Healy -- Large-scale surface coal mining occurs in the western end of the Nenana Coalfield, near Healy (Keystone, 1997). In the past, explosions from this coalfield have occasionally been located and cataloged by the USGS/NEIC. The largest suspected mining-induced event from this region that is listed in earthquake catalogs of the USGS/NEIC for 1973 -- March 2000 had ML = 3.3. We have not yet begun listing of Alaskan mining explosions in the "Routine Mining Seismicity in the United States".

ARIZONA

Clifton -- A large surface copper mine is situated near Clifton. Special analysis of a group of events with computed epicenters near Silver City, New Mexico, suggests that most of the epicenters are severely mislocated from true epicenters near Clifton. The special analysis suggests that the mislocations are a consequence of an unfavorable azimuthal distribution of stations recording the events, combined with the misidentification of Pg-phases as Pn-phases at stations to the north of the epicenters. The largest suspected explosion from southeastern Arizona or southwestern New Mexico that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.4.

Kayenta -- Large surface coal mines are located on the geomorphic feature named Black Mesa, south of Kayenta (Keystone, 1997). The source as defined by our epicenters extends many tens of kilometers away from Black Mesa proper. The large north-south spread of the calculated epicenters may be an artifact resulting from epicenter mislocations. This is suggested by the fact that the zone is parallel to the direction in which most epicenters are least well constrained, as inferred from the confidence ellipses associated with the epicenters. The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.1.

COLORADO

Craig -- Large-scale surface coal mining occurs south of Craig in the Uinta Basin. (Keystone, 1997). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.3.

Montrose -- Longwall mining of coal is conducted in underground mines northeast of Montrose (Keystone, 2000). The largest mine-associated seismic event from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.3. Induced seismic events of similar magnitude are also listed for this area in earthquake catalogs of the USGS/NEIC (see Mining-induced events in the earthquake catalogs of the USGS/NEIC).

Steamboat Springs -- Large-scale surface mining of coal occurs west of Steamboat Springs in the Green River Basin (Keystone, 1997). In addition, regionally recorded seismic signals are produced by roof-collapses that are deliberately induced by longwall mining in a large underground mine (Walter and others, 1996). Our epicenters near Steamboat Springs are probably biased eastward or northward by approximately ten kilometers. We have not isolated the cause of this bias. The largest suspected seismic event from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.9.

IDAHO

Soda Springs -- Explosions are recorded from phosphate mines in this region (Sue Nava, University of Utah Seismographic Stations, personal communication). The area also experiences a high level of seismicity that is unrelated to mining (Smith and Arabasz, 1991). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.7.

Wallace -- The Coeur d'Alene mining district is the site of frequent rockbursts (Sprenke and others, 1991). The largest suspected mining-induced event from this region that is listed in earthquake catalogs of the USGS/NEIC for 1973 -- March 2000 had ML = 3.6. Events from the Coeur d'Alene district have not yet been listed in catalogs of routine mining seismicity (see Mining-induced events in the earthquake catalogs of the USGS/NEIC).

KENTUCKY

Hazard -- Large-scale surface mining of coal occurs in eastern Kentucky (Keystone, 1997). Relatively large explosions are detonated in cast-blasting operations (Chapman and others, 1993). The lower frequency of mine explosions identified for eastern Kentucky relative to southern West Virginia may be due in part to the eastern Kentucky blasts being less well recorded by stations recording at the USGS/NEIC than blasts of the same size occurring in southern West Virginia. Location of shocks in eastern Kentucky is otherwise subject to the same difficulties as location of shocks in southern West Virginia. The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had mbLg(USGS) = 3.6.

MINNESOTA

Hibbing -- Relatively large explosions are associated with the open-pit mining of iron ore (Greenhalgh and others, 1980). Seismographic data recorded at the USGS/NEIC are not sufficient to detect or locate these events. The suspected explosions we have cataloged were originally detected and located with sparse data at the International Data Center and listed in their Reviewed Event Bulletin (REB). Our solutions are obtained with REB arrival-time data plus data from the USGS/NEIC station EYMN. The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had mbLg(USGS) = 3.4.

MONTANA

Colstrip -- Large-scale surface mining of coal occurs in eastern Montana near Colstrip (Keystone, 1997). We have evidence, however, that epicenters of events calculated to lie near Colstrip are actually associated with a mine near Decker (see below).

Decker -- Cast-blasting is conducted at a surface coal mine near Decker, and most events that we have located in the Decker/Colstrip region are probably associated with this mine. We have learned that the following events occurred near 45.12N, 106.92 W:

Jan 05, 2000, 20 02 05.3 UTC (our calculated location is 80 km NNE)

Feb 10, 2000, 23 04 59.6 UTC (our calculated location is 56 km NNE)

Apr 07, 2000, 19 03 37.8 UTC (our calculated location is 51 km NNE)

May 19, 2000, 20 24 19.3 UTC (our calculated location is 63 km NNE)

The mislocation of epicenters is principally the result of a poor azimuthal distribution of seismographic stations with respect to the mine in which the explosions are detonated.

The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.0.

NEW MEXICO

Farmington -- Large-scale surface mining of coal occurs north and west of Farmington in the San Juan Basin (Keystone, 1997). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.9.

Gallup -- Large-scale surface mining of coal occurs in the San Juan Basin north of Gallup (Keystone, 1997). The large northeast-southwest spread of the calculated epicenters is in part probably an artifact resulting from epicenter mislocations. This is suggested by the fact that the zone is parallel to the direction in which most epicenters are least well constrained, as inferred from the confidence ellipses associated with the epicenters. The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.1.

Silver City -- Open pit copper mining occurs near Silver City, but a special analysis of many of the epicenters with calculated epicenters near and south of Silver City suggests that most of the epicenters are severely mislocated from true epicenters near Clifton, Arizona (see above).

OHIO

Jackson -- Surface and underground coal mines, including some longwall operations, are situated in southeastern Ohio (Keystone, 1997). Relatively large explosions are detonated in cast-blasting operations (Chapman and others, 1993). The largest mining event from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had mbLg(USGS) = 3.6.

UTAH

Copperton -- The Bingham Canyon open-pit copper mine is near Copperton (Richins, 1979). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.8.

Price -- The Book Cliffs coalfield is north and east of Price and the Wasatch Plateau coalfield is west of Price. The area has long been a source of significant rockburst activity, with event magnitudes ranging up to approximately 4.0 (Arabasz and others, 1997). Some of the mines use longwall technology (Keystone, 2000). The largest suspected mining-associated event from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.6.

Vernal -- Explosions associated with phosphate mining occur in this region (Sue Nava, University of Utah Seismographic Stations, personal communication). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.6.

VIRGINIA

Big Stone Gap -- Large longwall coal mines are situated in southwesternmost Virginia. Some underground mines in southwestern Virginia and adjacent Kentucky border experience rockbursts (Martin Chapman, Virginia Polytechnic Institute and State University, personal communication). The largest suspected mining-associated event from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had mbLg(USGS) = 3.4. Earthquake catalogs of the USGS/NEIC for 1973 -- March 2000 contain mining-associated events from southwestern Virginia and adjacent Kentucky that have magnitudes as high as 4.3(MB) and 4.0(mbLg) (see Mining-induced events in the earthquake catalogs of the USGS/NEIC).

WASHINGTON

Centralia -- Large-scale surface mining of coal occurs in the Centralia-Chehalis coalfield (Keystone, 1997). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.3.

WEST VIRGINIA

Beckley -- Numerous surface and underground coal mines, including some longwall operations, are situated in southern West Virginia (Keystone, 1997). Relatively large explosions are detonated in cast-blasting operations (Chapman and others, 1993). Some underground mines in southwestern West Virginia experience rockburst activity (Martin Chapman, Virginia Polytechnic Institute and State University, personal communication).

We were provided independent information on three large, southern West Virginia, explosions by the company that owns the mine at which the explosions were detonated. The times and sizes of the explosions are as follows, together with our computed epicenters and magnitudes for the events:

05/22/97 @ 20:50 UTC; 2,353,674 pounds [computed O-time 20 49 30.2 ; lat 37.970 N; long 81.475 W; mbLg 3.4 (GS)]. Our location was approximately 11 km ENE of the independently known epicenter.

06/26/97 @ 21:13 UTC; 3,543,443 pounds [The explosion was not detected by the USGS/NEIC automatic event-detection algorithm. With benefit of company-provided information on the explosion, we found the explosion well-recorded on stations recording at the USGS/NEIC and computed lat 38.019 N; long 81.465 W; mbLg 3.4(GS). Our location was about 10 km east of the independently known epicenter. This event was well-recorded by the group of stations recording at the USGS/NEIC, but the automatic event-detection algorithm apparently tried to associate arrival-times from the large explosion with arrival-times from other regional explosions, and failed to identify a coherent pattern of arrival-times. The confusion of arrival-times from several independent explosions occurring at nearly the same time also hinders the reliable location of some explosions that are automatically detected by the USGS/NEIC event-detection algorithm.]

01/12/98 @ 21:56 UTC; 1,961,275 pounds [The explosion occurred when our mine-explosion monitoring was suspended. With knowledge that the explosion had occurred we found it in the USGS/NEIC data stream and computed O-time 21 56 12.4 ; lat 38.022N; long 81.329 W; mbLg 3.2 (GS)]. Our location was about 22 km east of the independently known epicenter.

The number of events we have located the Beckley region and elsewhere in the central Appalachians have been far fewer in 1999 -- 2000 than in 1997 . We believe that this apparent decrease in activity reflects the fact that key seismographic stations that were recording at the USGS/NEIC in 1997 were not recording in 1999-2000.

The largest suspected explosion from the Beckley region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had mbLg(USGS) = 3.4.

Morgantown -- Longwall mining of coal is conducted in several large underground mines near Morgantown (Keystone, 2000). The largest suspected longwall roof-collapse from northern West Virginia that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.9.

WYOMING

Gillette -- Many large surface coal mines are located in a north-south belt of strippable coal in the Southern Powder River Basin that passes near Gillette (Keystone, 1997). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.6.

Hanna -- Both surface and underground (longwall) coal mining occurs in the Hanna Basin near Hanna (Keystone, 1997). The largest suspected mining-associated event from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.6.

Kemmerer -- Large-scale surface mining of coal occurs in the Hams Fork Coalfield near Kemmerer (Keystone, 1997). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 2.8.

Rock Springs -- Large-scale surface mining of coal occurs in the Green River Basin near Rock Springs (Keystone, 1997). The largest suspected explosion from this region that is listed in the catalogs of routine mining seismicity for May 1997 -- March 2000 had ML(USGS) = 3.4. The largest mining-induced event from this region that is listed in earthquake catalogs of the USGS/NEIC for 1973 -- March 2000 had MB = 5.3 and was caused by a catastrophic roof-collapse in an underground trona mine (Pechmann and others, 1995; Swanson and Boler, 1995) (also see Mining-induced events in the earthquake catalogs of the USGS/NEIC).

REFERENCES

Arabasz, W.J., Nava, S.J., and Phelps, W.T., 1997, Mining seismicity in the Wasatch Plateau and Book Cliffs mining districts, Utah, USA: in Gibowicz, S.J., and Lasocki, S., eds., Rockbursts and Seismicity in Mines, Balkema, Rotterdam, p. 111-116.

Chapman, M.C., Huang, S., and Snoke, J.A., 1993, Single-station backazimuth estimation from P- and Rg- waves at regional distance in the central Appalachians: PL-TR-93-2228, Phillips Laboratory, 43 pp.

Fiscor, S., 2000, U.S. Longwall Census '99: 2000 Keystone Coal Industry Manual, Primedia, Chicago, p. 276-281.

Greenhalgh, S.A., Mooney, H.M., and Mosher, C.C., 1980, The Minnesota Seismic Network: Bulletin of the Seismological Society of America, v.70, p. 1347-1368.

Keystone, 1997, 1997 Keystone Coal Industry Manual, Intertec, Chicago, 800 pp.

Pechmann, J.C., Walter, W.R., Nava, S.J., and Arabasz, W.J., 1995, The February 3, 1995, ML 5.1 seismic event in the trona mining district of southwestern Wyoming: Seismological Research Letters, v. 66 (3), p. 25-34.

Richins, W.D., compiler, 1979, Data processing and analysis, in Arabasz, W.J., Smith, R.B., and Richins, W.D., eds., Earthquake Studies in Utah 1850 to 1978: Special Publication of the University of Utah Seismographic Stations, Salt Lake City, p. 79-90.

Smith, R.B., and Arabasz, W.J., 1991, Seismicity of the intermountain seismic belt: in Slemmons, D.B., Engdahl, E.R., Zoback, M.D., and Blackwell, D.D., eds., Neotectonics of North America: Boulder, Colorado, Geological Society of America, Decade Map Volume 1.

Sprenke, K.F., Stickney, M.C., Dodge, D.A., and Hammond, W.R., 1991, Seismicity and tectonic stress in the Coeur d'Alene Mining District, Bulletin of the Seismological Society of America, v. 81, p. 1145-1156.

Swanson, P.L., and F.M. Boler, 1995, The magnitude 5.3 seismic event and collapse of the Solvay Trona Mine: Analysis of pillar/floor failure stability. U.S. Bureau of Mines Open File Rept. 86-95.

Walter, W.R., Hunter, S.L., and Glenn, L.A., 1996, Preliminary report on LLNL Mine Seismicity Deployment at the Twentymile Coal Mine: UCRL-ID-122800, Lawrence Livermore National Laboratory, Livermore, California, 19 pp.

Names of Source Regions in Catalogs covering May-November, 1997

For catalogs covering May-November, 1997, epicenters of many of the suspected explosions are described in terms of generalized source regions. Use of these generalized source regions was discontinued for events occurring after November, 1997. Names of the generalized source regions were as follows:

ARIZONA- "Black Mesa." For computed epicenters in 36.0N-37.2N, 109.8W-110.8W .

COLORADO - "Near Craig." For computed epicenters in 40.0N-40.6N, 107.2W-108.2W.

COLORADO - "Near Steamboat Springs." For computed epicenters in 40.0N-40.6N, 106.5W-107.2W.

IDAHO - "Near Soda Springs." For explosions in 42.3N-43.1N, 110.8W-112.0W.

NEW MEXICO - "Near Farmington." For computed epicenters in 36.5N-37.2N, 107.8W-108.8W.

NEW MEXICO - "Near Gallup." For computed epicenters in 35.3N-36.0N, 108.4W-109.4W.

NEW MEXICO - "Near Silver City." For computed epicenters in 32.0N-33.3N, 107.8W-109.0W.

UTAH - "Near Copperton." For computed epicenters in 40.3N-40.8N, 112.0W-112.6W.

UTAH - "Near Vernal". For computed epicenters in 40.2N-41.0N, 109.0W-110.0W.

WASHINGTON - "Near Centralia."

WYOMING - "Near Kemmerer." For computed epicenters in 41.5N-42.2N, 110.0W-111.0W.

WYOMING - "Near Rock Springs." For computed epicenters in 41.2N-42.2N, 108.0W-110.0W.

WYOMING - "Southern Powder River Basin." For computed epicenters in 43.2N-44.5N, 104.7W-105.7W.

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