Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
권호 표지
DOI QR코드

DOI QR Code

Seismic Response from Microtremor of Chogye Basin, Korea

초계분지의 상시미동 지진응답

  • Lee, Heekyoung (Division of Earth Environmental System Science, Pukyong National University) ;
  • Kim, Roungyi (Division of Earth Environmental System Science, Pukyong National University) ;
  • Kang, Tae-Seob (Division of Earth Environmental System Science, Pukyong National University)
  • 이희경 (부경대학교 지구환경시스템과학부) ;
  • 김령이 (부경대학교 지구환경시스템과학부) ;
  • 강태섭 (부경대학교 지구환경시스템과학부)
  • Received : 2017.02.22
  • Accepted : 2017.03.06
  • Published : 2017.05.31
Download PDF
⟨ Previous Next ⟩

Abstract

Chogye basin, which is surrounded by country rock, has a closed-basin form. In such a basin, incident seismic energy can form multiply reflected waves, thus causing energy concentration to occur at this closed-basin area. Microtremor measurement survey was performed at the Chogye basin, which is located in Chogye-myeon and Jeokjungmyeon, Hapcheon-gun, Gyeongsangnam-do, Republic of Korea. Microtremor data were transformed into the frequency domain, and then the horizontal-to-vertical spectral ratios (HVSR) were calculated. Fundamental resonance frequencies were estimated from the HVSR results for every observation point. Using the empirical relationship between site period and thickness for sediment sites in Korea known from the previous study, the distribution of sediment thickness of the Chogye basin was estimated from the fundamental resonance frequencies. Being compared with the mountainous rim with steep slope, the measurement points inside the basin have low values of the fundamental resonance frequency with the minimum of 1.03 Hz, which corresponds to the thickness of sedimentary layer with the maximum depth of about 100 m. A three-dimensional basin model was constructed for bedrock topography of the Chogye basin by an interpolation of basin depths estimated at each measurement site.

초계분지는 그릇과 같이 주변이 모암으로 둘러싸여 있는 닫힌 분지의 형태를 갖고 있다. 이러한 닫힌 분지에서는 입사한 지진에너지가 분지 내에서 다중 반사파를 형성하며 에너지의 집중이 발생하기 쉽다. 경상남도 합천군 초계면과 적중면에 위치한 타원형의 초계분지를 대상으로 상시미동 관측 조사를 수행하였다. 상시미동 관측 자료를 주파수 영역으로 변환하고 수평 대 수직성분 스펙트럼 비를 계산하였다. 이 결과로부터 각 관측 지점에 대한 기본 공명주파수를 측정하였다. 이전 연구에서 알려진 우리나라 퇴적층에 대한 고유주기와 두께의 경험적인 상관관계를 이용하여, 기본 공명 주파수로부터 초계분지의 퇴적층 두께 분포를 결정하였다. 급한 경사를 갖는 산지로 둘러싸인 분지 외곽에 비하여, 분지 내부의 관측점에서 기본 공명주파수가 최소 1.03 Hz로 낮으며, 이에 상응하는 퇴적층이 두껍고, 그 깊이는 최대 약 100 m에 이른다. 각 관측점에서 결정한 분지 깊이를 내삽하여 초계분지의 기반암 지형에 대한 3차원 분지 모델을 작성하였다.

Keywords

References

  1. Cha, Y. H., Kang, J. S., and Jo, C.-H., 2006, Application of linear-array microtremor surveys for rock mass classification in urban tunnel design, Exploration Geophysics, 37, 108-113. https://doi.org/10.1071/EG06108
  2. Chang, J. H., 2002, Granite Erosion Landforms of Korea, Sungshin University Press (in Korean).
  3. Chang, K. H., 1968, Explanatory text of the geological map of Habcheon sheet (1:50,000), Geological Survey of Korea, 21p (in Korean).
  4. Chavez-Garcia, F. J., and Kang, T.-S., 2014, Lateral heterogeneities and microtremors: Limitations of HVSR and SPAC based studies for site response, Engineering Geology, 174, 1-10. https://doi.org/10.1016/j.enggeo.2014.02.007
  5. Choi, K.-S., Lee, S.-W., and Lee, Y.-A., 2001, Circular landform and basin of the Chogye.Jeokjung area in Hapcheon-gun, 2001 Fall Conference of the Geological Society of Korea (in Korean).
  6. Choi, K.-S., Lee, S.-W., and Lee, Y.-S., 2004, A study on the sub-stratum structure in and around the Chogye-myon and Jukjung-myon of Hapchun-gun by gravity analysis, The Journal, College of Education, Pusan National University, 43, 201-227 (in Korean with English abstract).
  7. Delgado, J., Lopez Casado, C., Giner, J., Estevez, A., Cuenca, A., and Molina, S., 2000, Microtremors as a geophysical exploration tool: Applications and limitations, Pure and Applied Geophysics, 157, 1445-1462. https://doi.org/10.1007/PL00001128
  8. Field, E. H., Hough, S. H., and Jacob, K. H., 1990, Using microtremors to assess potential earthquake site response: A case study in flushing meadows New York City, Bull. Seismol. Soc. Am., 80, 1456-1480.
  9. Field, E., and Jacob, K., 1993, The theoretical response of sedimentary layers to ambient seismic noise, Geophysical Research Letters, 20, 2925-2928. https://doi.org/10.1029/93GL03054
  10. Goldstein, P., Dodge, D., Firpo, M., and Minner, L., 2003, SAC2000: Signal processing and analysis tools for seismologists and engineers, Invited contribution to The IASPEI International Handbook of Earthquake and Engineering Seismology, Edited by W. H. K Lee, H. Kanamori, P. C. Jennings, and C. Kisslinger, Academic Press, London.
  11. Hinzen, K.-G., Weber, B., and Scherbaum, F., 2004, On the resolution of H/V measurements to determine sediment thickens, a case study across a normal fault in the Lower Rhine Embayment. Germany, J. Earthq. Eng., 8, 909-926.
  12. Hong, M. H., and Kim, K. Y., 2010, H/V Spectral-ratio Analysis of Microtremors in Jeju Island, Geophysi. and Geophys. Explor., 13, 144-152 (in Korean with English abstract).
  13. Hwang, S., and Yoon, S.-O., 2016, Geomorphic development of the Jeogchung.Chogye basin and inner alluvial fan, Hapcheon, South Korea, J. Korean Assoc. Regional Geographers, 22, 225-239 (in Korean with English abstract).
  14. Hwang, Y. G., and Kim, K. Y., 2006, Shallow shear-wave velocities using the microtremor survey method, J. Eng. Geology, 16, 381-392 (in Korean with English abstract).
  15. Ibs-von Seht, M., and Wohlenberg, J., 1999, Microtremor measurements used to map thickness of soft sediments, Bull. Seismol. Soc. Am., 89, 250-259.
  16. Jung, H., Kim, H. J., Jo, B. G., and Park, N. R., 2010, The microtremor HVSRs in the SW Korean Peninsula I: Characteristics of the HVSR peak frequency and amplification, J. Korean Earth Sci. Soc., 31, 541-554 (in Korean with English abstract). https://doi.org/10.5467/JKESS.2010.31.6.541
  17. Kanai, K., Tanaka, T., and Osada, K., 1954, Measurements of micro-tremors 1, Bull. Earthq. Res. Inst., Tokyo University, 32, 199-210.
  18. Kang, T.-S., and Shin, J. S., 2011, Stability and correlation properties of microtremor response, Geosciences Journal, 15, 95-103. https://doi.org/10.1007/s12303-011-0002-3
  19. Kim, K. W., and Lee, Y. J., 1969, Explanatory text of the geological map of Changryeong sheet (1:50,000), Geological Survey of Korea, 18p (in Korean).
  20. Kim, K. Y., and Hong, M. H., 2010, Shear-wave velocity structures at the foot of Mt. Halla using the spatial autocorrelation method, J. Geological Soc. Korean, 46, 39-48 (in Korean with English abstract).
  21. Kim, K. Y., and Hong, M. H., 2012, Shear-wave velocity structure of Jeju Island, Korea, Geosciences Journal, 16, 35-45. https://doi.org/10.1007/s12303-012-0004-9
  22. Kim, S. K., 1991, Microtremor and underground structure, J. Eng. Geology, 1, 109-120 (in Korean with English abstract).
  23. Kim, S. K., and Hwang, M. W., 2002, Estimation of subsurface structure and ground response by microtremor, J. Korean Earth Sci. Soc., 23, 380-392 (in Korean with English abstract).
  24. Lermo, J., and Chavez-Garcia, F. J., 1993, Site effects evaluation using spectral ratios with only one station, Bull. Seismol. Soc. Am., 83, 1574-1594.
  25. Lermo, J., Rodriguez, M., and Singh, S. K., 1988, The Mexico earthquake of september 19, 1985 - natural period of sites in the valley of Mexico from microtremor measurements and strong motion data, Earthquake Spectra, 4, 805-814. https://doi.org/10.1193/1.1585503
  26. Nakamura, Y., 1989, A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface, Quarterly Report of the Railway Technical Research Institute, 30, 25-33.
  27. Ohta, Y., Kagami, H., Goto, N., and Kudo, K., 1978, Observation of 1 to 5-s microtremors and their application to earthquake engineering. Part I: Comparison with long-period accelerations at the Tokachi-oki earthquake of 1968, Bull. Seismol. Soc. Am., 68, 767-779.
  28. Ozalaybey, S., Zor, E., Ergintav, S., and Centiz Tapirdamaz, M., 2011, Investigation of 3-D basin structures in the Izmit Bay area (Turkey) by single-station microtremor and gravimetric methods, Geophy. J. Int., 186, 883-894. https://doi.org/10.1111/j.1365-246X.2011.05085.x
  29. Parolai, S., Bormann, P., and Milkereit, C., 2002, New relationship between vs, thickness of sediments, and resonance frequency calculated by the H/V ratio of seismic noise for the Cologne area (Germany), Bull. Seismol. Soc. Am., 92, 2521-2527. https://doi.org/10.1785/0120010248
  30. Paudyal, Y. R., Yatabe, R., Bhandary, N. P., and Dahal, R. K., 2013, Basement topography of the Kathmandu Basin using microtremor observation, J. Asian Earth Sci., 62, 627-637. https://doi.org/10.1016/j.jseaes.2012.11.011
  31. SESAME, 2004, Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations: Measurements, processing and interpretation, SESAME European Research Project WP12 - Deliverable D23.12, European Commission - Research General Directorate, Project No. EVG1-CT-2000-00026 SESAME.
  32. Sun, C.-G., 2010, Suggestion of additional criteria for site categorization in Korea by quantifying regional specific characteristics on seismic response, Geophysi. and Geophys. Explor., 13, 203-218 (in Korean with English abstract).
  33. Wathelet, M., 2006, H/V measurements, Geopsy Manual, http://www.geopsy.org/documentation/geopsy/hv.html (December 12, 2016 Accessed).
  34. Yun, W. Y., Park, S.-C., and Kim, K. Y., 2013, Near-surface shear-wave velocities derived from microtremors and teleseismic data at the Hwacheon seismic station, Geophysi. and Geophys. Explor., 16, 190-195 (in Korean with English abstract). https://doi.org/10.7582/GGE.2013.16.3.190