A Study of the Dynamic Amplification Characteristics of the Domestic Seismic Observation Sites Using Coda Wave

Coda파를 이용한 국내 관측소지반의 동적 증폭특성에 관한 연구

  • 김준경 (세명대학교 소방방재학과) ;
  • 이준대 (세명대학교 토목공학과)
  • Received : 2009.09.09
  • Accepted : 2009.11.20
  • Published : 2009.12.01

Abstract

For more reliable estimation of soil-structure interaction and seismic source and attenuation properties, site amplification function should be considered. This study use the Nakamura's method (1989) for estimating site amplification though various methods for the same purpose have been proposed. This method was originally applied to the surface waves of background noise and therefore there are some limitation for applications to general wave energy. However, recently this method has been extended and applied to the S wave energy successfully. This study applied the method to the coda wave energy which is equivalent to the backscattered S wave energy. We used more than 60 observed ground motions from 5 earthquakes which occurred recently, with magnitude range from 3.6 to 5.1 Each station showed characteristic site amplification property in low-, high- and resonance frequency ranges. In the case of comparing these results to those from S wave energy, lots of information to the site classification work can be gained. Moreover, removal of site amplification can give us more reliable seismic source parameters.

지진원 및 구조물과 지반상호간의 동적 특성을 보다 신뢰성 있게 도출하기 위해 지반의 증폭특성은 반드시 고려되어야하는 요소이다. 지반증폭 특성을 분석할 때 여러 가지 방법이 제시되어 있으나 본 연구에서는 Nakamura(1989)에 의해 제시된 방법을 적용하였다. 본 방법은 얕은 지반의 상시미동의 표면파 특성을 이해하기 위해 제시되어 한계점이 존재하나 근래에 와서 S파 등에 적용되어 지반의 동적인 증폭 특성연구에 많이 이용되고 있다. 일반적으로 S파가 이용되고 있으나 본 연구에서는 지진파 에너지인 Coda 파에 새로이 적용하였다. 최근 국내에 설치된 지진 관측기에 관측된 5개 지진(규모 3.6-5.1)의 약 60 여개의 관측자료를 이용하여 지진관측소 각각 지반의 동적인 증폭 특성을 분석하였다. 관측소마다 저진동수, 고진동수 및 우월주파수가 서로 다른 증폭특성을 보여주었다. 본 연구 결과 관측지반진동에서 지반 고유의 증폭특성을 제거하면 지진원 변수를 보다 신뢰성 있게 도출할 수 있다.

Keywords

Acknowledgement

Supported by : 기상지진개발사업단

References

  1. 김준경 (2009), 오대산지진 자료를 이용한 국내 관측소 부지의 증폭특성 연구, 한국지진공학회 논문집, Vol. 13, No. 1, pp. 27-34. https://doi.org/10.5000/EESK.2009.13.1.027
  2. 이준대, 김준경 (2009), 관측지진파를 이용한 지반증폭특성 사례분석, 한국지반환경공학회 논문집, Vol. 10, No. 1, pp. 35-41.
  3. Atkinson, G. M. and John F. Cassidy (2000), Integrated Use of Seismograph and Strong-Motion Data to Determine Soil Amplification: Response of the Fraser River Delta to the Duvall and Georgia Strait Earthquakes, Bulletin Seismological. Society. America. Vol. 90, No. 4, pp. 1028-1040. https://doi.org/10.1785/0119990098
  4. Bonilla, L., Steidl, J., Lindley, G., Tumarkin, A. and Archuleta, R. (1997), Site Amplification in the San Fernando Valley, California. Variability of Site-effect Estimation using the S-wave, Coda, and H/V methods, Bulletin Seismological. Society. America. Vol. 87, No. 3, pp. 710-730.
  5. Boore and Joyner (1997), Site-Amplifications for Generic Rock Sites, Bulletin Seismological. Society. America. Vol. 87, pp. 327-341.
  6. Borcherdt, R. (1970), Effects of Local Geology on Ground Motion Near San Francisco Bay, Bulletin Seismological. Society. America. Vol. 60, No. 1, pp. 29-61.
  7. Hartzell, S., Cranswick, E., Frankel, Carver, D. and M. Meremonte (1997), Variability of Site Response in the Los Angeles Urban Area, Bulletin Seismological. Society. America. Vol. 87, No. 6, pp. 1377-1400.
  8. ICBO 1997 (1997), Unifrom Building Code, Volume 2- Structural Engineering Design Provisions, International Conference of Building Officials, pp. 492.
  9. Kato, K., Aki, K. and Takemura, M. (1995), Site Amplification from Coda Waves: Validation and Application to S-wave Site Response, Bulletin Seismological. Society. America. Vol. 85, No. 2, pp. 467-477.
  10. Nakamura, Y. (1989), A Method for Dynamic Characteristics Estimation of Subsurface using Microtremor on the Ground Surface, QR RTRI, Vol. 30, No. 1, pp. 25-33.
  11. NEHERP (1997), Recommended Provisions for Seismic Regulation for New Building and Other Structures, FEMA 302/303, part 1 (Provisions) and Part 2 (Commentary), pp. 1-55.
  12. Phillips, S. C. and Keiiti Aki (1986), Site Amplification of Coda Waves from Local Earthquakes in Central California, Bulletin Seismological. Society. America. Vol. 76, No. 3. pp. 627-648.
  13. Rogers, A. M., Borcherdt, R. D., Covington, P. A. and Perkins, D. M. (1984), A Comparative Ground Response Study near Los Angeles using Recordings of Nevada Nuclear Tests and the 1971 San Fernando earthquake, Bulletin Seismological. Society. America. Vol. 74, No. 5, pp. 1925-1949.
  14. Su, F., John, G., Anderson, James, N., Brune, and Yuehua Zeng (1996), A Comparison of Direct S-Wave and Coda-Wave Site Amplification Determined from Aftershocks of the Little Skull Mountain Earthquake, Bulletin Seismological. Society. America. Vol. 86, No. 4, pp. 1006-1018.
  15. Tucker, B. D. and J. L. King (1984), Dependence of Sedimentfilled Valley Response on Input Amplitude and Valley Properties, Bulletin Seismological. Society. America. Vol. 74, No. 1, pp. 153-165.