Observed Seismicity - University of Kentucky

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4 Discussion Table 1. Seismic stations in western Kentucky. Station Longitude Latitude Depth Recorder Sensor Location (degrees) (degrees) (m) FMKY –88.909 36.664 100 KEWS L-4C Flugham, Ky. LLKY –88.097 36.992 36 KEWS L-4C Land-Between-the-Lakes, Ky. LOKY –88.295 37.237 5 KEWS L-4C Lockhart Bluff, Ky. BLKY –89.015 37.184 24 NetDAS L-4C Ballard Wildlife Management Area LAKY –88.969 37.079 48 NetDAS L-4C La Centre, Ky. GAKY –88.897 37.044 48NetDAS L-4C Gage, Ky.* ARKY –88.997 36.748 48 NetDAS VLF-3 Arlington, Ky. DEKY –89.084 36.974 61 NetDAS VLF-3 Ballard Detention Center BAKY –88.997 36.886 45 NetDAS L-4C Bardwell, Ky. VSAP –88.822 37.124 30 NetDAS VLF-3 Paducah Gaseous Diffusion Plant, Ky.* *Installation not yet complete Table 2. Central U.S. earthquakes recorded between January 1 and May 31, 2003. Magnitude Date Time Latitude Longitude Depth Location (UTC) 3.0 05/02/03 08:10:13 37.970 88.650 0.6 Macedonia, Ill. 4.0 04/30/03 04:56:22 35.940 89.920 23.8 Blytheville, Ark. 4.6 04/29/03 08:59:38 34.508 85.612 15.0 Menlo, Ga. occurred far from the new seismic stations. The new seismic stations are designed to capture data on earthquakes in western Kentucky, the Jackson Purchase Region in particular, that are significant for seismichazard assessment of that area. The June 6, 2003, Bardwell, Ky., earthquake occurred at about 8:30 a.m. (EDT), with a magnitude of M4.0. The initial location and focal depth determined by the U.S. Geological Survey were 36.890N/89.010W and 0.1 km, respectively. The recordings from the earthquake were collected from the stations on June 12, 2003. The data were evaluated and analyzed immediately. We determined the location of the earthquake to be 36.88N/88.98W, which put the quake near Bardwell (Fig. 5). Detailed parameters are listed in Table 4. The focal depth was only about 2.3 km beneath the surface; such a shallow earthquake, with a magnitude of M4.0, is very unusual in the central United States. In comparison, another earthquake with a magnitude of M4.0, occurring on April 30, 2003, near Blytheville, Ark., had a focal depth of about 23.8 km. Discussion Figure 10 shows the locations of earthquakes recorded in the central United States since 1974. Earthquakes occur sporadically over a large region, with the exception of the New Madrid Seismic Zone, where earthquakes concentrate along the known faults (Fig. 10). Many earthquakes occurred in the Jackson Purchase Region (Fig. 10), but the pattern of seismicity does not show that the earthquakes in western Kentucky are directly connected to the New Madrid faults (Fig. 10). It has been long suspected that
Discussion 5 Figure 2. Recordings of the Blytheville, Ark., earthquake at station ARKY. earthquakes in the Jackson Purchase Region tend to be shallow (< 5.0 km), but this could not be proven because of the lack of a dense seismic network. Earthquakes occurring in the New Madrid Seismic Zone between January 1 and June 30, 2003, are shown in Figure 11. Appendix B lists detailed parameters of the earthquakes. Except for the June 6, 2003, Bardwell earthquake, all are concentrated along the New Madrid faults. The largest earthquakes are the April 30, 2003, Blytheville, Ark., and the June 6, 2003, Bardwell, Ky., earthquakes, both with magnitude M4.0. The focal depths for the two Figure 3. Recording of the Menlo, Ga., earthquake at station BLKY.
Page 1 and 2: Observed Seismicity (Earthquake Act
Page 3 and 4: Contents Executive Summary.........
Page 5 and 6: Executive Summary Although it has n
Page 7: Data Evaluation and Analysis 3 stal
Page 11 and 12: Discussion 7 Table 3. Seismic and s
Page 13 and 14: Discussion 9 Figure 9. Seismic reco
Page 15 and 16: North Discussion 11 91° 38° 88°
Page 17 and 18: Appendix A 13 Appendix A: Providing
Page 19 and 20: Appendix B 15 Appendix B: Earthquak

Observed Seismicity - University of Kentucky

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