Journal of the Earthquake Engineering Society of Korea (한국지진공학회논문집)

Earthquake Engineering Society of Korea (한국지진공학회)
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Characterizing the Performance of New Seismic Stations in Southeastern Region, Korea Using Seismic Noise Levels

배경잡음 수준 분석에 의한 동남권 신규 관측소 성능 특성 평가

  • Shin, Jin Soo (Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Seong, Yun-Jeong (Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Son, Minkyung (Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources)
  • 신진수 (한국지질자원연구원 지진연구센터) ;
  • 성윤정 (한국지질자원연구원 지진연구센터) ;
  • 손민경 (한국지질자원연구원 지진연구센터)
  • Received : 2019.07.23
  • Accepted : 2019.10.14
  • Published : 2019.11.01
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Abstract

We performed seismic noise level analysis to access the proper functioning of 11 newly established seismic stations in the southeastern region of Korea. One-hour long segments of seismograms were selected from the continuous data of the 3 elements for 61 days from March 1, 2019. For each segment of data, the power spectral density (PSD) was estimated from the continuous back ground noise data of the 3 elements for periods ranging from 0.02~100 s. The median noise levels (NLs) of the stations were compared with the new noise model (NNM) of USGS and NLs of station TJN installed in a tunnel on a granite basement. We observed that the NLs of the newly installed seismometers were between the upper and lower limit of the NNM. In a comparison with the noise level of station TJN, the new seismometers had their own noteworthy features. The NLs from accelerometers (Epi-sensors) were ~ 40 dB higher than the NLs from velocimeters (STS-sensors) for periods > 10 s, which is because the small and light Epi-sensors are sensitive to environmental changes. Daily and weekly variations in spectral noise level were observed clearly in short periods < 1 s, and these are considered to be related to human activities. The seismometers in boreholes showed ~20 dB weaker NLs in the cultural noise band. The NLs of accelerometers at a depth of 30 m were also much lower by 30 dB for long periods > 10 sec. Overall the functioning of the new velocimeter and accelerometer stations was reliable for periods ranging from 0.02~100 s and 0.02~10 s, respectively.

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References

  1. Ringdal F, Bungum H. Noise level variation at NORSAR and its effect on detectability. Bulletin of the Seismological Society of America. 1977;67:79-49.
  2. McNamara DE, Buland RP. Ambient noise levels in the continental United States. Bulletin of the Seismological Society of America. 2004;94:1517-1527. https://doi.org/10.1785/012003001
  3. Sheen DH, Shin JS, Kang TS. Sesimic noise level variation in South Korea. Geoscience Journal. 2009;13(2):183-190. https://doi.org/10.1007/s12303-009-0018-0
  4. Young CJ, Chael EP, Withers MM, Aster RC. A comparison of the high-frequency (> 1 hz) surface and subsurface noise environment at three sites in the United States. Bulletin of the Seismological Society of America. 1996;86:1516-1528.
  5. Longuet-Higgins MS. A theory of the origin of microseisms. Philosophical Transactions of the Royal Society London, Series A. 1950;243:1-35. https://doi.org/10.1098/rsta.1950.0012
  6. Hasselmann K. A statistical analysis of the generation of microseisms. Review of Geophysics. 1963;1:177-209. https://doi.org/10.1029/RG001i002p00177
  7. Peterson J. Observations and modeling of background seismic noise. U.S. Geological Survey, Open-File Report 93-322;1993:1-95.
  8. Ramirez EE, Vidal-Villegas JA, Nunez-Leal MA, Ramirez-Hernandez J, Mejia-Trejo A, Rosas-Verdugo E. Seismic noise levels in northern Baza California, Mexico. Bulletin of the Seismological Society of America. 2019;109(2):610-620. https://doi.org/10.1785/0120180155
  9. Govoni A, Bonatto L, Capello M, Cavaliere A, Chiarabba C, D'Alema E, Danesi S, Lovati S, Margheriti L, Massa M, et al.. AlpArray-Italy:Site description and noise characterization. Adv. Geosci. 2017;43:39-52. https://doi.org/10.5194/adgeo-43-39-2017
  10. Koper KD, Burlacu R. The fine structure o f double-frequency microseisms recorded by seismometers in North America, J. Geophys. Res. Solid Earth. 2015;120:1677-1691. https://doi.org/10.1002/2014JB011820
  11. Son M, Shin JS, Kim G, Cho CS. Epicenter relocation of two 2013 earthquake sequences in the Yellow Sea, Korea, using travel-time double-differences and Lg-wave cross-correlation. Geosciences Journal. 2015 June;19(2):295-303. https://doi.org/10.1007/s12303-014-0038-2
  12. Kim KH, Ree JH, Kim YH, Kim S, Kang SY, Seo W. Assessing whether the 2017 Mw 5.4 Pohang earthquake in South Korea was an induced event. Science. 2018 Jun;360:1007-1009. https://doi.org/10.1126/science.aat6081
  13. Han M, Kim HJ, Kang SY, Kim KH, Yoon SH, Kyung JB. Detection of microearthquakes and identification of their causative structures in the eastern offshore region of South Korea. Tectonophysics. 2019 Jan;750(5):36-44. https://doi.org/10.1016/j.tecto.2018.11.003
  14. Cho BJ, Sheen DH, Jo BG, Park SC, Hwang EH. Development of a standard background noise model for broadband seismic stations of KMA, Journal of the Geological Society of Korea. 2009;45(2):124-141.