Economic and Environmental Geology (자원환경지질)

The Korean Society of Economic and Environmental Geology (대한자원환경지질학회)
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Geoelectrical Structure and Groundwater Distribution in the South-eastern Region of Jeju Island Revealed by Controlled Source Audio-frequency Magneto Telluric (CSAMT) survey

인공송신원 가청주파수 자기지전류 탐사를 이용한 제주 동남부의 전기비저항 구조 및 지하수 분포 조사

  • Yang, Jun-Mo (Department of Earth Science Education, Seoul National University) ;
  • Kwon, Byung-Doo (Department of Earth Science Education, Seoul National University) ;
  • Lee, Hei-Soon (Department of Science Education, Gyeongin National University of Education) ;
  • Song, Sung-Ho (Rural Research Institute, KRC) ;
  • Park, Gyeo-Soon (Department of Earth Science Education, Seoul National University) ;
  • Lee, Kyu-Sang (Rural Research Institute, KRC)
  • 양준모 (서울대학교 지구과학교육과) ;
  • 권병두 (서울대학교 지구과학교육과) ;
  • 이희순 (경인교육대학 과학교육과) ;
  • 송성호 (한국농촌공사 농어촌연구원) ;
  • 박계순 (서울대학교 지구과학교육과) ;
  • 이규상 (한국농촌공사 농어촌연구원)
  • Published : 2007.02.28
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Abstract

We have performed the CSAMT survey to examine the geoelectrical structure and groundwater distribution for two survey lines across the south-eastern region of Jeju Island. Three kinds of 1-D inversion techniques were employed taking account of the geological situation around the observation sites, and their inversion results were concurrently compared and analyzed to improve the reliability of interpretation. The resultant inverted resistivity structures reveals the three-layered structure, which is composed of the layers with a high-low-lower resistivity from the surface downward. Through the comparison of the inverted resistivity model and core log of deep borehole nearby observation sites, the lithology of each inverted layer was inferred. The first layer and second layer corresponded to the basaltic layer with a thickness of $100{\sim}250m$, and the third layer to the Seoguipo Formation and the U Formation; the thickness of the Seoguipo Formation could not be estimated due to the limitation of investigation depth and little resistivity difference between both Formations. Nevertheless, the Seoguipo Formation, which is strongly associated with the groundwater system in the south-eastern region of Jeju Island, showed the conspicuous spatial continuity from the middle mountain area to coastal area.

제주도 동남부의 전기비저항 구조 및 지하수 분포 형태를 조사하기 위해 제주도 중산간에서 남동방향으로 해안 지역을 횡단하는 두 측선에 대해 인공송신원 자기지전류탐사를 수행하였다. 측점들이 위치한 지질학적 상황을 고려하여 세 종류의 일차원 역산 기법을 도입하였고, 해석의 신뢰성 향상을 위해 각 역산 결과를 비교, 분석하였다. 이 과정으로부터 도출된 제주 동남부의 개략적인 전기비저항 구조는 고비저항-저비저항-보다 저비저항을 갖는 3층 구조였다. 역산 결과와 측점 부근의 심부 시추 자료의 비교를 통해 제주도 동남부의 각 층별 암상이 개략적으로 추정되었다: 지질학적 층서의 관점에서 제 1층과 2층은 두께 100-250m의 현무암층에, 제 3층은 서귀포층 및 U층에 대응하는데, 서귀포층의 두께는 조사심도가 충분히 깊지 않고 서귀포층과 U층의 전기비저항 차이가 작기 때문에 추정할 수 없었다. 그러나 주대수층과 밀접하게 관련 있는 서귀포층은 제주도 동남부 지역의 경우 중산간 지역부터 해안 지역까지 뚜렷한 공간적 연속성을 보여주었다.

Keywords

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