Electric and Electromagnetic Surveys of the Hongseong Fault Zone

홍성 단층대에서의 전기, 전자 탐사 연구

  • Kwon, Byung-Doo (Department of Earth Science Education, Seoul National University) ;
  • Lee, Heui-Soon (Department of Science Education, Gyeongin National University of Education) ;
  • Park, Gye-Soon (Department of Earth Science Education, Seoul National University) ;
  • Oh, Seok-Hoon (Marine Meteorology & Earthquake Research Lab, Meteorogical Reseorch Institute) ;
  • Lee, Choon-Ki (Department of Earth Science Education, Seoul National University)
  • 권병두 (서울대학교 사범대학 지구과학교육과) ;
  • 이희순 (경인교육대학교 과학교육과) ;
  • 박계순 (서울대학교 사범대학 지구과학교육과) ;
  • 오석훈 (기상연구소 해양기상지진연구실) ;
  • 이춘기 (서울대학교 사범대학 지구과학교육과)
  • Published : 2003.06.30

Abstract

We have investigated the electric resistivity structure of the fault zone located in the Hongseong area where a big earthquake with M 5.0 occurred in 1978. Usually, Electric and Electromagnetic methods are broadly operated in the field of engineering works since these methods are effective to understand the distribution of geological weak zones - fault or fracture zones. We have conducted the dipole-dipole array resistivity method and MT(magnetotelluric) method and interpreted the resistivity distribution of the fault zone with the aid of various inversion methods. An MT survey was performed at 18 points along a 2.9 km survey line perpendicular to the fault line and a magnetic dipole source was used to enhance the S/N ratio in the high frequency. A Electric dipole-dipole array resistivity survey with the dipole length of 50 meters was carried out perpendicular to the fault. In view of two survey results, the fault marks the boundary between two opposite resistivity structures, especially the low resistivity zone is exhibited deeply through the prospective fault line. The result that the low resistivity zone is located at the center of the fault zone corresponds with the fact that the fault zone of the Hongseong area is active. We expect these results to provide basic information about the physical properties of fault zones in Korea.

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