Journal of the Korean Geophysical Society (지구물리)

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

A study on the characteristics of difference arrow using three-dimensional MT(Magneto-Telluric) modeling

3차원 전도체의 공간적 위치 및 크기에 따른 차이 지시자의 특성 연구

  • Yang, Jun-Mo (Marine Meteorology & Earthquake Res. Lab., Meteorological Research Institute) ;
  • Oh, Seok-Hoon (Marine Meteorology & Earthquake Res. Lab., Meteorological Research Institute) ;
  • Lee, Duk-Kee (Marine Meteorology & Earthquake Res. Lab., Meteorological Research Institute) ;
  • Kwon, Byung-Doo (Department of Earth Science Education, Seoul National University) ;
  • Youn, Yong-Hoon (Marine Meteorology & Earthquake Res. Lab., Meteorological Research Institute)
  • 양준모 (기상연구소 해양기상지진연구실) ;
  • 오석훈 (기상연구소 해양기상지진연구실) ;
  • 이덕기 (기상연구소 해양기상지진연구실) ;
  • 권병두 (서울대학교 지구과학교육과) ;
  • 윤용훈 (기상연구소 해양기상지진연구실)
  • Published : 20021200
Download PDF
⟨ Previous Next ⟩

Abstract

The three-dimensional MT(Magneto-Telluric) modeling is performed to examine the validity of difference arrow of GDS(Geomagnetic Depth Sounding) survey, In this paper, we investigate the validity of the difference arrow on three configurations of conductors; which is located 1) at surface, 2) at the deep part and 3) vertically extended f개m surface to the deep part, respectively, For conductors located at surface, the validity of difference arrows is certified in our numerical model when long periods over 40 minutes are used or the distance between sea and conductor is over 150 km. However, for conductors located at the deep part, the validity of difference arrow is dependent on the size of conductors. Further, if the size of conductor is adequately larger than that of our model, we recognize the possibility that the mutual coupling of them influences up to longer periods, Moreover, in case of conductors which is vertically extended from surface to the deer part, the mutual coupling of them is reinforced for all periods, especially for longer periods, so that the validity of difference arrow is considerably in doubt. Therefore, to remove the known conductor effect such as the sea effect from the observed induction arrow, the mutual coupling between them must be examined. The difference arrow that certifies the validity in this way can only provide the Subsurface information based on physical supports.

지자기수직탐사(GDS; Geomagnetic Depth Sounding)에서의 차이 지시자(difference arrow)의 유용성을 조사하기 위하여 3차원 MT(Magneto-Telluric)모델링을 수행하였다. 본 연구에서는 3차원 전도체와 해양의 공간적 위치 및 전도체의 크기에 따른 차이 지시자의 특성을 조사하였다. 전도체가 지표에 존재할 때 본 연구에서 사용된 모델의 경우 사용된 주기가 장주기(40분 이상)거나 해양과의 거리가 멀어지면(150 km 이상) 상호결합이 무시할 정도로 약해 차이 지시자가 유의미하였다. 그러나 전도체가 심부에 매몰된 경우 차이 지시자의 유용성은 그 크기에 의존적이며 전도체가 충분히 큰 경우 상호결합이 장주기까지 영향을 미칠 수 있다는 가능성을 확인하였다. 또한 수직적으로 확장된 전도체의 경우 전 주기에서 상호결합이 강화되어 장주기에서도 차이 지시자의 유용성을 확신할 수 없었다. 따라서 획득된 유도 지시자로부터 해양처럼 이미 알고 있는 전도체의 효과를 제거하기 위해서는 전도체 간의 상호 결합에 대한 정보가 요구되며 유용성이 확인된 차이 지시자는 물리적 지지를 바탕으로 지하 구조에 대한 정보를 제공할 것이다.

Keywords

References

  1. 자원환경지질학회 no.5 지자기수직 탐사에 의한 한반도 주변의 전기전도도 구조 오석훈;양준모;이덕기;남재철
  2. 대한지구물리학회 no.2 지자기 전달함수의 로버스트 추정 양준모;오석훈;이덕기;윤용훈
  3. Phys. Earth Planet. Inter. v.60 On the behaviour of the induction arrows over a buried conductive plate-a numerical model study Agarwal, A.K.;Dosso, H.W.
  4. Phys. Earth Planet. Inter. v.81 Numerical estimation of the sea effect on the distribution of induction arrows in the Japanese island arc Bapat, V.J.;Segawa, J.;Honkura, Y.;Traits, P.
  5. Phys. Earth Planet. Inter. v.99 EM responses of an elongated conductor near an ocean-analogue model studies Chen, J.;Dosso, H.W.
  6. Phys. Earth Planet. Inter. v.70 The coast effect response in geomagnetic field measurements Dosso, H.W.;Meng, Z.W.
  7. Phys. Earth Planet. Inter v.97 Difference electromagnetic induction arrow responses in New Zealand Dosso, H.W.;Chen, J.;Chamalaun, F.H.;McKnight, J.D.
  8. Radio Sci. v.29 Three-dimensional electromagnetic modeling using finite difference equations; the magnetotelluric example Mackie, R.L.;Smith, J.T.;Madden, T.R.
  9. Geophys. J. R. Astro. Soc. v.6 The influence of continents and ocean on geomagnetic variations Parkinson, W.D.
  10. Phys. Earth Planet. Inter. v.119 Magnetovariational soundings across the South Island of New Zealand: difference induction arrow and the Southern Alps conductor Pringle, D.;Ingham M.;McKnight J.D.;Chamalaun F.H.
  11. Solid earth geomagnetism Rikitake, T.;Honkura, Y.
  12. Bull. Scripps lnst. Oceanogr. v.13 Anomalies of geomagnetic variations in the southwestern United States Schmucker, U.
  13. Geopys. Res. Lett. v.24 Electrical conductivity anomalies beneath the western sea of Kyushu, Japan Shimoizumi, M.;Mogi, T.;Nakada, M.;Yukutake, T.;Handa, S.;Tanaka, Y.;Utada, H.
  14. Geophys. J. R. Astron. Soc. v.51 Bimodal electromagnetic induction in non-uniform thin sheets with an application to the Northern Pyrenean induction anomaly Vassuer, G.;Weidelt, P.
  15. Geophys. v.37 The magnetotelluric method in the exploration of sedimentary basin Vozoff, K.
  16. Phys. Earth Planet. Inter. v.65 Is addition of induction vectors meaningful? Weaver, J.T.;Agarwal, A.K.
  17. Geophys. Pura Appl. v.52 Geomagnetische Tiefentellurik Wiese, H.
  18. J. Geophys. v.52 Inductive coupling between idealized conductors and its significance for the geomagnetic coast effect Wolf, D.