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Discrimination between Earthquakes and Explosions Recorded by the KSRS Seismic Array in Wonju, Korea

원주 KSRS 지진 관측망에 기록된 지진과 폭발 식별 연구

  • Jeong, Seong Ju (Earthquake Research Center, Geological Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Che, Il-Young (Earthquake Research Center, Geological Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Kang, Tae-Seob (Department of Earth and Environmental Sciences, Pukyong National University)
  • 정성주 (한국지질자원연구원 국토지질연구본부 지진연구센터) ;
  • 제일영 (한국지질자원연구원 국토지질연구본부 지진연구센터) ;
  • 강태섭 (부경대학교 지구환경과학과)
  • Received : 2014.06.23
  • Accepted : 2014.07.24
  • Published : 2014.08.31

Abstract

This study presents a procedure for discrimination of artificial events from earthquakes occurred in and around the Korean Peninsula using data set in the Wonju KSRS seismograph network, Korea. Two training sets representing natural and artificial earthquakes were constructed with 150 and 56 events, respectively, with high signal to noise ratio. A frequency band, Pg(4-6 Hz)/Lg(5-7 Hz), which is optimal for the discrimination of seismic sources was derived from the two-dimensional grid of Pg/Lg spectral amplitude ratio. The corrections for the effects of earthquake magnitude and hypocentral distance were carried out for improvement of discrimination capability. For correcting the effect of magnitude dependence due to the inverse proportionality of corner frequency to seismic moment, the Brune's source spectrum was subtracted from the observation spectrum. The spectrum was corrected using the optimal damping coefficient to remove damping effect with the hypocentral distance. The effect of locally varying spectrum ratio was cancelled correcting variation of wave propagation along the ray path. The performance in discrimination between training sets of natural and artificial events was compared using the Mahalanobis distance in each step of correction. The procedure of magnitude, distance, and path corrections show clear improvements of the discrimination results with increasing Mahalanobis distance, from 1.98 to 3.01, between two training sets.

Acknowledgement

Supported by : 한국지질자원연구원

References

  1. Brune, J. N., 1970, Tectonic stress and spectra of seismic shear waves from earthquakes, Journal of Geophysical Research, 75, 4997-5009. https://doi.org/10.1029/JB075i026p04997
  2. Che, I. Y., 2003, A study on the discrimination between earthquake and artificial explosion by using Cheorwon seismic and infrasound array data, Korea, Ph.D. thesis, Yonsei University, 157p.
  3. Che, I. Y., Jeon, J. S., and Lee, H. I., 2003, Discrimination between earthquake and explosion by using seismic spectral characteristics and linear discriminant analysis, Proceedings of Earthquake Engineering Society of Korea 2003 Fall Conference, 13-19.
  4. Chung, S. Y., Shim, B. O., Kim, G. B., Kang, D. H., and Park, H. Y., 2000, The characteristics of groundwater quality in the Youngsan and Sumjin River basins using geostatistical methods, Journal of the Korean Society of Grounwater Environment, 7, 125-132.
  5. Fisk, M. D., Taylor, S. R., Patton, H. J., and Walter, W. R., 2008, Applications of a next-generation MDAC discrimination procedure using two-dimensional grids of regional P/S spectral ratios, Proceedings of the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, 583-592.
  6. Fisk, M. D., Taylor, S. R., Walter, W. R., and Randall, G. E., 2009, Seismic event discrimination using two-dimensional grids of regional P/S spectral ratios: Applications to Novaya Zemlya and the Korean Peninsula, Proceedings of the 2009 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, 465-474.
  7. Gitterman, Y., Pinsky, V., and Shapira, A., 1998, Spectral classification methods in monitoring small local events by the Israel seismic network, Journal of Seismology, 2, 237-256. https://doi.org/10.1023/A:1009738721893
  8. Hanks, T. C., and Kanamori, H., 1979, A moment magnitude scale, Journal of Geophysical Research, 84, 2348-2350. https://doi.org/10.1029/JB084iB05p02348
  9. Hartse, H., Taylor, S., Phillips, W., and Randall, G., 1997, A preliminary study of regional seismic discrimination in Central Asia with emphasis on Western China, Bulletin of the Seismological Society of America, 87, 551-568.
  10. Jeong, S. J., Che, I. Y., Kim, I. H., and Kang, T. S., 2014, A seismic discrimination of explosions from earthquakes using two-dimensional grids of P/Lg spectral ratios and its application to the Sangwon, North Korea, area, in preparation.
  11. Joswig, M., 1999, Seismic Signal Classification: Preprocessing, Progress report: 07/1999 - 12/1999, VATAT Grant.
  12. Kang, I. B., Kim, S. B., Suh, M. C., and Jun, M. S., 2000, Study on discrimination between natural earthquakes and man-made explosions using Wonju KSRS data, Journal of the Korean Geophysical Society, 3, 25-36.
  13. Kim, S. G., Park, Y. C., and Kim, W. Y., 1998, Discrimination of small earthquakes and artificial explosions in the Korean Peninsula using Pg/Lg ratios, Geophysical Journal International, 134, 267-276. https://doi.org/10.1046/j.1365-246x.1998.00575.x
  14. Kim, W. Y., Aharonian, V., Lerner-Lam, A. L., and Richards, P. G., 1997, Discrimination of earthquakes and explosions in Southern Russia using regional high-frequency three-component data from the IRIS/JSP Caucasus Network, Bulletin of the Seismological Society of America, 87, 569-588.
  15. Koch, K., 2002, Seismic event identification of earthquakes and explosions in Germany using spectral Lg ratios, Pure and Applied Geophysics, 159, 759-778. https://doi.org/10.1007/s00024-002-8658-2
  16. Phillips, W. S., 1999, Empirical path corrections for regional phase amplitudes, Bulletin of the Seismological Society of America, 89, 384-393.
  17. Rodgers, A. J., and Walter, W. R., 2002, Seismic discrimination of the May 11, 1998 Indian nuclear test with short-period regional data from station NIL (Nilore, Pakistan), Pure and Applied Geophysics, 159, 679-700. https://doi.org/10.1007/s00024-002-8654-6
  18. Rodgers, A. J., Walter, W. R., Schultz, C. A., Myers, S. C., and Lay, T., 1999, A comparison of methodologies for representing path effects on regional P/S discriminants, Bulletin of the Seismological Society of America, 89, 394-408.
  19. Stump, B. W., Riviere-Barbier, F., Chernoby, I., and Koch, K., 1994, Monitoring a Test Ban Treaty presents scientific challenges, EOS, Transactions, American Geophysical Union, 75, 265-273.
  20. Taylor, S. R., and Denny, H. D., 1991, An analysis of spectral differences between NTS and Shagan River nuclear explosions, Journal of Geophysical Research, 96, 6237-6245. https://doi.org/10.1029/91JB00147
  21. Taylor, S. R., Denny, M. D., Vergino, E. S., and Glaser, R. E., 1989, Regional discrimination between NTS explosions and western U.S. earthquakes, Bulletin of the Seismological Society of America, 79, 1142-1176.
  22. Taylor, S. R., and Hartse, H. E., 1997, An evaluation of generalized likelihood ratio outlier detection to identification of seismic events in Western China, Bulletin of the Seismological Society of America, 87, 824-831.
  23. Taylor, S. R., and Hartse, H. E., 1998, A procedure for estimation of source and propagation amplitude corrections for regional seismic discriminants, Journal of Geophysical Research, 103, 2781-2789. https://doi.org/10.1029/97JB03292
  24. Taylor, S. R., Sherman, N. W., and Denny, M. D., 1988, Spectral discrimination between NTS explosions and western United States earthquakes at regional distance, Bulletin of the Seismological Society of America, 78, 1563-1579.
  25. Taylor, S. R., Velasco, A. A., Hartse, H. E., Phillips, W. S., Walter, W. R., and Rodgers, A. J., 2002, Amplitude corrections for regional seismic discriminants, Pure and Applied Geophysics, 159, 623-650. https://doi.org/10.1007/s00024-002-8652-8
  26. Walter, W. R., Mayeda, K. M., and Patton, H. J., 1995, Phase and spectral ratio discrimination between NTS earthquakes and explosions. Part I: Empirical observations, Bulletin of the Seismological Society of America, 85, 1050-1067.
  27. Walter, W. R., and Priestley, K. F., 1991, High frequency P wave spectra from explosions and earthquakes, in Explosion Source Phenomenology, American Geophysical Monograph, 65, 219-228.
  28. Walter, W. R., and Taylor, S. R., 2001, A Revised Magnitude and Distance Amplitude Correction (MDAC2) Procedure for Regional Seismic Discriminants: Theory and Testing at NTS, Lawrence Livermore National Laboratory report.
  29. Xie, J., and Patton, H. J., 1999, Regional phase excitation and propagation in the Lop Nor region of central Asia and implications for P/Lg discriminants, Journal of Geophysical Research, 104, 941-954. https://doi.org/10.1029/1998JB900045