Geophysics and Geophysical Exploration (지구물리와물리탐사)

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

DOI QR Code

Analysis of Static Shift and its Correction in Magnetotelluric Surveys

MT 탐사에서의 정적효과 및 보정법 분석

  • Hanna Jang (Department of Energy and Mineral Resources Engineering, Sejong University) ;
  • Yoonho Song (Deep Subsurface Research Center, Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources (KIGAM)) ;
  • Myung Jin Nam (Department of Energy and Mineral Resources Engineering, Sejong University)
  • 장한나 (세종대학교 에너지자원공학과) ;
  • 송윤호 (한국지질자원연구원 국토우주지질연구본부 심층처분환경연구센터) ;
  • 남명진 (세종대학교 에너지자원공학과)
  • Received : 2024.02.19
  • Accepted : 2024.05.27
  • Published : 2024.05.31
Download PDF
⟨ Previous Next ⟩

Abstract

In magnetotelluric (MT) surveys, small inhomogeneities near the surface cause a static shift in which apparent resistivities shift regardless of frequency. As the static shift in MT data leads to errors in subsurface structure interpretation, many studies have been conducted over the past few decades to mitigate or remove the distortions it caused. The most representative method involves removing static shifts from the data before inversion. Conversely, static shifts can be corrected during inversion or included in the inversion process. In addition, other geophysical data can be used to remove static shifts. However, the correction methods are limited to one-dimensional (1D) static responses, and limitations remain in two- or three-dimensional (2D or 3D) interpretation of distorted MT data owing to static shifts. This study provides a foundation for future studies on static shift by analyzing several previously published methods.

자기지전류(magnetotelluric, MT) 탐사 시, 지표면 부근의 작은 불균질체가 존재할 경우 겉보기비저항이 주파수와 무관하게 이동하는 정적효과(static shift)가 발생한다고 알려져 있다. 이러한 정적효과가 자료에 포함되어 있으면 지하 구조 해석에 오류가 발생하기 때문에 정적효과에 의한 왜곡을 해결하기 위한 연구가 지난 수십년 동안 수행되어 왔다. 가장 대표적인 방법으로는 역산 전에 MT 자료에서 정적효과를 제거하기 위해 보정하는 방법이 있다. 이와 달리, 역산 과정에서 정적효과를 역산의 변수로 포함시켜 그 크기를 추정하거나 따로 정적효과를 추정하지 않고 역산 과정에서 보정을 수행하기도 한다. 이외에도 다른 물리탐사 기법을 통해 얻은 자료를 사용하여 MT 탐사 정적효과를 제거할 수 있다. 하지만 지금까지 연구된 보정법들은 1차원적인 정적인 반응에만 국한되어 있어 2차원이나 3차원의 자료를 역산하고 해석하는 데에는 여전히 한계가 있다. 이 논문에서는 지금까지 MT 자료에서 정적효과를 처리하는 여러 방법들에 대해 분석하여 향후 정적효과 관련 연구를 위한 기초를 제공하고자 한다.

Keywords

Acknowledgement

이 논문은 2024년도 정부(원자력안전위원회)의 재원으로 사용후핵연료관리핵심기술개발사업단 및 한국원자력안전재단의 지원을 받아 수행된 연구사업임(RS-2021-KN066110).

References

  1. Arnason, K., 2008, The magneto-telluric static shift problem, ISOR-Iceland GeoSurvey, Reykjavik, report, ISOR-08088.
  2. Bahr, K., 1988, Interpretation of the magnetotelluric impedance tensor: Regional induction and local telluric distortion, J. Geophys., 62, 119-127.
  3. Berdichevsky, M. N., and Dmitriev, V. I., 2002, Magnetotellurics in the Context of the Theory of Ill-Posed Problems, Society of Exploration Geophysicists.
  4. Berdichevsky, M. N., Vanyan, L. L., Kuznetsov, V. A., Levadny, V. T., Mandelbaum, M. M., Nechaeva, G. P., Okulessky, B. A., Shilovsky, P. P., and Shpak, I. P., 1980, Geoelectrical model of the Baikal region, Phys. Earth Planet. Inter., 22(1), 1-11.
  5. Bibby, H. M., Caldwell, T. G., and Brown, C., 2005, Determinable and non-determinable parameters of galvanic distortion in magnetotellurics, Geophys. J. Int., 163(3), 915-930.
  6. Bostick, F. X., and Smith, H. W., 1962, Investigation of large-scale inhomogeneities in the earth by the magnetotelluric method, Proceedings of the IRE, 50(11), 2339-2346.
  7. Cagniard, L., 1953, Basic theory of the magnetotelluric method of geophysical prospecting, Geophysics, 18, 605-645.
  8. Cai, J., Chen, X., Xu, X., Tang, J., Wang, L., Guo, C., Han, B., and Dong, Z., 2017, Rupture mechanism and seismotectonics of the Ms6.5 Ludian earthquake inferred from three-dimensional magnetotelluric imaging, Geophys. Res. Lett., 44(3), 1275-1285.
  9. Cantwell, T., 1960, Detection and Analysis of Low Frequency Magnetotelluric Signals, Ph.D. thesis, Massachusetts Institute of Technology.
  10. Comeau, M. J., Unsworth, M. J., and Cordell, D., 2016, New constraints on the magma distribution and composition beneath Volcan Uturuncu and the southern Bolivian Altiplano from magnetotelluric data, Geosphere, 12(5), 1391-1421.
  11. Cressie, N., 2015, Statistics for Spatial Data, John Wiley & Sons.
  12. Cumming, W., and Mackie, R., 2010, April, Resistivity imaging of geothermal resources using 1D, 2D and 3D MT inversion and TDEM static shift correction illustrated by a Glass Mountain case history, In Proceedings World Geothermal Congress (pp. 25-29), Bali, Indonasia.
  13. Dampney, C. N. G., 1969, The equivalent source technique. Geophysics, 34(1), 39-53.
  14. Daud, Y., Nuqramadha, W. A., Fahmi, F., Sesesega, R. S., Pratama, S. A., and Munandar, A., 2019, Resistivity characterization of the Arjuno-Welirang volcanic geothermal system (Indonesia) through 3-D Magnetotelluric inverse modeling, J. Asian Earth Sci., 174, 352-363.
  15. deGroot-Hedlin, C., 1991, Removal of static shift in two dimensional by regularized inversion, Geophysics, 56, 2102-2106.
  16. Dey, S., 2005, Magnetotelluric Survey in the Northern Part of Eastern Ghats Mobile Belt and the Southern Part of Singhbhum Craton Across the Archaean-Proterozoic Contact, Eastern India, Ph.D. Thesis, IIT Kharagpur, India.
  17. Edwards, R. N., and Nabighian, M. N., 1991, The magnetometric resistivity method, Electromagnetic Methods in Applied Geophysics: Volume 2, Application, Part A and B, 47-104.
  18. Egbert, G. D., and Booker, J. R., 1986, Robust estimation of geomagnetic transfer functions, Geophys. J. Int., 87(1), 173-194.
  19. Falgas, E., Ledo, J., Benjumea, B., Queralt, P., Marcuello, A., Teixido, T., and Marti, A., 2011, Integrating hydrogeological and geophysical methods for the characterization of a deltaic aquifer system, Surv. Geophys., 32, 857-873.
  20. Farquharson, C. G., and Craven, J. A., 2009, Three-dimensional inversion of magnetotelluric data for mineral exploration: An example from the McArthur River uranium deposit, Saskatchewan, Canada, J. Appl. Geophy., 68(4), 450-458.
  21. Farquharson, C. G., Oldenburg, D. W., Haber, E., and Shekhtman, R., 2002, An algorithm for the three-dimensional inversion of magnetotelluric data, In SEG Technical Program Expanded Abstracts 2002 (pp. 649-652), Society of Exploration Geophysicists.
  22. Gamble, T. D., Goubau, W. M., and Clarke, J., 1979, Magnetotellurics with a remote magnetic reference, Geophysics, 44(1), 53-68.
  23. Groom, R. W., and Bailey, R. C., 1989, Decomposition of magnetotelluric impedance tensors in the presence of local three-dimensional galvanic distortion, J. Geophys. Res. Solid Earth, 94(B2), 1913-1925.
  24. Han, N. R., Nam, M. J., Kim, H. J., Song, Y. H., and Suh, J. H., 2007, A Comparative Study of 3D MT Modeling Methods, Geophys. and Geophys. Explor., 10(2), 154-160. (in Korean with English abstract)
  25. Hersir, G. P., Arnason, K., and Vilhjalmsson, A. M., 2015, 3D inversion of magnetotelluric (MT) resistivity data from Krysuvik high temperature geothermal area in SW Iceland, In Proceedings of the 38th Workshop on Geothermal Reservoir Enineering (p. 14), Stanford: Stanford Univ..
  26. Hill, G. J., Bibby, H. M., Ogawa, Y., Wallin, E. L., Bennie, S. L., Caldwell, T. G., Keys, H., Bertrand, E. A., and Heise, W., 2015, Structure of the Tongariro Volcanic system: Insights from magnetotelluric imaging, Earth Planet. Sci. Lett., 432, 115-125.
  27. Hu, X., Peng, R., Wu, G., Wang, W., Huo, G., & Han, B., 2013, Mineral exploration using CSAMT data: Application to Longmen region metallogenic belt, Guangdong Province, China, Geophysics, 78(3), B111-B119.
  28. Huang, X. Y., Deng, J. Z., Chen, X., Wang, X. X., Chen, H., and Yu, H., 2019, Magnetotelluric extremum boundary inversion based on different stabilizers and its application in a high radioactive waste repository site selection, Appl. Geophy., 16(3), 367-377.
  29. Jeong, J., Jang, H., and Nam, M. J., 2023, Application Analysis on Past Cases of Radioactive Waste Disposal Site Selection based on Geo-electric and Electromagnetic Surveys, J. Korean Soc. Miner. Energy Resour. Eng., 60(2), 112-128. (in Korean with English abstract)
  30. Jones, A. G., 1988, Static shift of magnetotelluric data and its removal in a sedimentary basin environment, Geophysics, 53(7), 967-978.
  31. Kim, H. J., 1995, Inversion of Geophysical Data with Robust Estimation, Economic and Environmental Geology, 28(4), 433-438. (in Korean with English abstract)
  32. Lajaunie, C., and Bejaoui, R., 1991, Sur le Krigeage des Fonctions Complexes, ENSMP.
  33. Ledo, J., Queralt, P., and Pous, J., 1998, Effects of galvanic distortion on magnetotelluric data over a three-dimensional regional structure, Geophys. J. Int., 132(2), 295-301.
  34. Lee, S. K., Lee, T. J., Uchida, T., Park, I. H., Song, Y. H., and Cull, J., 2010, Two-dimensional analysis of MT data across Northern Victoria, Australia, Geophys. and Geophys. Explor., 13(4), 407-415 (in Korean with English abstract).
  35. Madarasi, A., Fusi, B., and Pracser, E., 2011, Fractured granite investigation by surface magnetotelluric and subsurface DC resistivity tomography, In 6th Congress of the Balkan Geophysical Society, European Association of Geoscientists & Engineers, pp. cp-262.
  36. Mansoori, I., Oskooi, B., and Pedersen, L. B., 2015, Magnetotelluric signature of anticlines in Iran's Sehqanat oil field, Tectonophysics, 654, 101-112.
  37. Marwan, Yanis, M., Idroes, R., and Ismail, N.,2019, 2D inversion and static shift of MT and TEM data for imaging the geothermal resources of Seulawah Agam Volcano, Indonesia, GEOMATE J., 17(62), 173-180.
  38. McLeod, J., Ferguson, I., Craven, J., Roberts, B., and Giroux, B., 2018, Pre-injection magnetotelluric surveys at the Aquistore CO2 sequestration site, Estevan, Saskatchewan, Canada, Int. J. Greenhouse Gas Control, 74, 99-118.
  39. Mogi, T., Katsura, I., and Nishimura, S., 1991, Magnetotelluric survey of an active fault system in the northern part of Kinki District, Southwest Japan, J. Struct. Geol., 13(2), 235-240.
  40. Mwakirani, R., Simiyu, C., and Gichira, J., 2012, Application of transient electromagnetics in static shift correction for magnetotellurics data case study: Paka geothermal prospect in kenya, Transactions, 36, 1013-1016.
  41. Nam, M. J., 2006, A study on 3D Topographic Effects in Magnetotelluric Surveys, Ph.D. Thesis, Seoul National University (in Korean with English abstract).
  42. Newman, G. A., Hohmann, G. W., and Anderson, W. L., 1986, Transient electromagnetic response of a three-dimensional body in a layered earth, Geophysics, 51(8), 1608-1627.
  43. Ogawa, Y., and Uchida, T., 1996, A two-dimensional magnetotelluric inversion assuming Gaussian static shift, Geophys. J. Int., 126(1), 69-76.
  44. Ogawa, Y., Mishina, M., Goto, T., Satoh, H., Oshiman, N., Kasaya, T., Takahashi, Y., Nishitani, T., Sakanaka, S., Uyeshima, M., Takahashi, Y., Honkura, Y., and Matsushima, M., 2001, Magnetotelluric imaging of fluids in intraplate earthquake zones, NE Japan back arc, Geophys. Res. Lett., 28(19), 3741-3744.
  45. Ogaya, X., Ledo, J., Queralt, P., Marcuello, A., and Quinta, A., 2013, First geoelectrical image of the subsurface of the Hontomin site (Spain) for CO2 geological storage: A magnetotelluric 2D characterization, Int. J. Greenhouse Gas Control, 13, 168-179.
  46. Osman, M. M., El-Qady, G. M., Abdel Fattah, T., Rashed, M., and Mohamdeen, M., 2021, Enhancement the VES models based on the TEM measurements and the application of static shift corrections: case study from Egypt, NRIAG J. Astron. geophys., 10(1), 279-289.
  47. Pedersen, L. B., and Engels, M., 2005, Routine 2D inversion of magnetotelluric data using the determinant of the impedance tensor, Geophysics, 70(2), G33-G41.
  48. Pellerin, L., and Hohmann, G. W., 1990, Transient electromagnetic inversion: a remedy for magnetotelluric static shifts, Geophysics, 55, 1242-1250.
  49. Santilano, A., Godio, A., and Manzella, A., 2018, Particle swarm optimization for simultaneous analysis of magnetotelluric and time-domain electromagnetic data, Geophysics, 83(3), E151-E159.
  50. Sasaki, Y., 2004, Three-dimensional inversion of static-shifted magnetotelluric data, Earth, Planets and Space, 56, 239-248.
  51. Sharma, S. P., and Biswas, A., 2011, Global nonlinear optimization for the estimation of static shift and interpretation of 1-D magnetotelluric sounding data, Ann. Geophys., 54(3), 249-264.
  52. Singer, B. S., 1992, Correction for distortions of magnetotelluric fields: limits of validity of the static approach, Surv. Geophys., 13, 309-340.
  53. Song, Y., Lee, T. J., and Uchida, T., 2006, Effect of remote reference on audio-frequency magnetotelluric data, J. Korean Soc. Miner. Energy Resour. Eng., 43(1), 44-54 (in Korean with English abstract).
  54. Spitzer, K., 2001, Magnetotelluric static shift and direct current sensitivity, Geophys. J. Int., 144(2), 289-299.
  55. Stephen, J., Gokarn, S. G., Manoj, C., and Singh, S. B., 2003, Effects of galvanic distortions on magnetotelluric data: Interpretation and its correction using deep electrical data, J. Earth Syst. Sci., 112, 27-36.
  56. Sternberg, B. K., Washburne, J. C., and Pellerin, L., 1988, Correction for the static shift in magnetotellurics using transient electromagnetic soundings, Geophysics, 53(11), 1459-1468.
  57. Szarka, L., and Menvielle, M., 1997, Analysis of rotational invariants of the magnetotelluric impedance tensor, Geophys. J. Int., 129, 133-142.
  58. Tang, W., Li, Y., Oldenburg, D. W., and Liu, J., 2014, October, Magnetotelluric static shift correction using an equivalent source technique, In SEG Technical Program Expanded Abstracts 2014, 697-701.
  59. Tong, X. Z., Liu, J. X., Sun, Y., and Guo, Z. W., 2010, Three-dimensional Magnetotelluric Forward Modeling for Static-shifted Model, Progress In Electromagnetics Research, 433-436.
  60. Torres-Verdin, C., and Bostick, F. X., 1992, Principles of spatial surface electric field filtering in magnetotellurics: electromagnetic array profiling (EMAP), Geophysics, 57, 603-622.
  61. Tournerie, B., Chouteau, M., and Marcotte, D., 2007, Magnetotelluric static shift: Estimation and removal using the cokriging method, Geophysics, 72(1), F25-F34.
  62. Tripaldi, S., Siniscalchi, A., and Spitzer, K., 2010, A method to determine the magnetotelluric static shift from DC resistivity measurements in practice, Geophysics, 75(1), F23-F32.
  63. Tseng, K. H., Ogawa, Y., Nurhasan, Tank, S. B., Ujihara, N., Honkura, Y., Terada, A., Usui, Y., and Kanda, W., 2020, Anatomy of active volcanic edifice at the Kusatsu-Shirane volcano, Japan, by magnetotellurics: hydrothermal implications for volcanic unrests, Earth, Planets and Space, 72, 1-11.
  64. Uchida, T., 1999, Three-dimensionality of magnetotelluric data in the Kakkonda geothermal field, northern Japan, In Proc. Second Internat. Symposium on Three-dimensional Electromagnetics (3DEM-2), Salt Lake City, 1999.
  65. Wackernagel, H., 2003, Multivariate geostatistics: an introduction with applications, Springer Science & Business Media.
  66. Wahba, G., 1990, Spline models for observational data, Society for industrial and applied mathematics.
  67. Wannamaker, P. E., Booker, J. R., Filloux, J. H., Jones, A. G., Jiracek, G. R., Chave, A. D., Tarits, P., Waff, H. S., Egbert, G. D., Young, C. T., Stodt, J. A., Martinez, M. G., Law, L. K., Yukutake, T., Segawa, J. S., White, A., and Green Jr, A. W., 1989, Magnetotelluric observations across the Juan de Fuca subduction system in the EMSLAB project, J. Geophys. Res. Solid Earth, 94(B10), 14111-14125.
  68. Wannamaker, P. E., Hohmann, G. W., and SanFilipo, W. A., 1984a, Electromagnetic modeling of three-dimensional bodies in layered earths using integral equations, Geophysics, 49(1), 60-74.
  69. Wannamaker, P. E., Hohmann, G. W., and Ward, S. H., 1984b, Magnetotelluric responses of three-dimensional bodies in layered earths, Geophysics, 49, 1517-1533.
  70. Yang, J., Kwon, B. D., Lee, D. K., Song, Y. H., and Youn, Y. H., 2005, An improvement of MT transfer function estimates using by pre-screening scheme based on the statistical distribution of electromagnetic fields, Korean Society of Earth and Exploration Geophysicists, 273-280 (in Korean with English abstract).
  71. Zhang, K., Lu Q., and Wei, W., 2013, A new static shift correction method of magnetotelluric--based on the analysis of 3D forwarding results, Near Surface Geophysics Asia Pacific Conference, Beijing, China, 398-401.
  72. Zhang, K., Wei, W., Lu, Q., Wang, H., and Zhang, Y., 2016, Correction of magnetotelluric static shift by analysis of 3D forward modelling and measured test data, Explor. Geophys., 47(2), 100-107.
  73. Zhou, J., Wang, X., Zhang, J., and Ruan, S., 2015, Estimation and removal of magnetotelluric static shift, In International Workshop and Gravity, Electrical & Magnetic Methods and their Applications, Chenghu, China, 442-445.