활성단층조사에서 전기비저항탐사 활용 = Application of Electrical Resistivity Surveys in Active Fault Investigation

국문 초록 (Abstract)

국내에서 제4기 지층으로 피복되어 있는 활성단층조사에 2차원 전기비저항탐사가 널리 활용되고 있지만, 지층의 전기비저항 분포로부터 활성단층의지질특성을 해석하는데 있어서 주관적 경험에 의존하고 있어 체계적인 해석 정립이 필요하다. 따라서 이 논설에서는 제4기 퇴적물로 피복되어 있는 남부 양산단층과 공주단층 북동부의 두 곳에 위치한 활성단층을 대상으로 2차원과 3차원 전기비저항탐사를 실시하고, 지층의 전기비저항 분포를 바탕으로 활성단층대의 지질특성과 전기비저항의 관련성에 대해서 살펴보았다. 그 결과, 단층면을 경계로 좌우에 다른 암종이 분포하고 있거나, 동일한 암종내에 지진활동에 의한 파쇄대가 단층면의 한쪽에 발달되어 있는 경우 2차원 전기비저항 분포 패턴이 수직적인 형태를 가지고 있으며, 상대적으로 고비저항과 저비저항의 경계에 활성단층면이 위치하고 있음을 알 수 있었다. 또한 단층은 선구조의 지질특성을 가지고 있기 때문에 파쇄대의 공간적 분포를이해하는데 3차원 전기비저항 분포가 유용함을 확인하였다. 그러나 3차원탐사는 현장 작업 및 해석에 많은 노력이 필요하기 때문에 국내 활성단층조사에 적용한 사례가 거의 없어 향 후 3차원탐사 기술 도입이 요구되고 있다.

다국어 초록 (Multilingual Abstract)

Despite the common use of 2D electrical resistivity surveys to investigate active faults buried under Quaternary sediments in Korea, interpretation of the geological characteristics of these faults from resistivity distributions often relies on subjective experience. This reliance on subjective interpretations can lead to inconsistencies and inaccuracies. Therefore, a more systematic and objective approach is required to enhance the reliability and accuracy of geological interpretations. In this study, 2D and 3D electrical resistivity surveys were conducted on two active faults, in the southern Yangsan Fault and the northeastern part of the Gongju Fault, both of which are covered by Quaternary sediments. The relationship between the geological characteristics of the active fault zone and the electrical resistivity was examined, based on the resistivity distribution within the strata. As a result, this study found that the 2D electrical resistivity distribution pattern takes on a vertical form when different rock types are distributed on either side of the fault plane boundary, or when a fracture zone caused by seismic activity is developed on one side of the fault plane within the same rock type. The active fault plane is located at the boundary between areas of relatively high and low resistivity. In addition, because faults exhibit the geological characteristic of being a linear structure, it was found that the 3D electrical resistivity distribution is useful for understanding the spatial distribution of fracture zones. However, because 3D surveys require considerable effort in both fieldwork and interpretation, their application in domestic active fault investigations has been limited. Therefore, the introduction and further development of 3D exploration technology are required in the future.

참고문헌 (Reference)

• 1 최성자 ; 김용식 ; 천영범 ; 고경태, "The First Discovery of Quaternary Fault in the Western Part of the South Yangsan Fault-Sinwoo Site" 52 (52): 251-258, 2019
• 2 Cheon, Y., "Structural architecture and late Cenozoic tectonic evolution of the Ulsan Fault Zone, SE Korea : New insights from integration of geological and geophysical data" 11 : 1-14, 2023
• 3 기원서 ; 황재하 ; 김복철 ; 김유홍 ; 송교영, "Structural Characteristics of Quaternary reverse faulting on the Eupcheon Fault, SE Korea" 43 : 311-333, 2007
• 4 Park, S. G., "Relationship between electrical resistivity and physical properties of rocks" 2016
• 5 조인기, "Recent Trend in Electrical Resistivity Method" 57 (57): 506-526, 2020
• 6 김영석 ; 손문 ; 최진혁 ; 최정헌 ; 성영배 ; 이진현, "Processes and challenges for the production of Korean active faults map" 56 : 113-134, 2020
• 7 Kyung, J. B., "Paleoseismological study on the midnorthern part of Ulsan fault by trench method" 7 : 81-90, 1997
• 8 Lee, K., "On the Seismic activity of the Yangsan fault" 21 (21): 38-44, 1985
• 9 KOBAYASHITAKAO ; 선창완 ; 최진혁, "Near-surface fault investigation by Ground Penetrating Radar(GPR)surveys" 58 (58): 445-455, 2022
• 10 Kim, C. -M., "Long-Term weakening processes and short-term seismic slip behavior of an intraplate mature fault zone: a case study of the Yangsan Fault, SE Korea" 127 : e2021-JB023154, 2022
• 11 최채현 ; 최진혁 ; 방은석 ; 이호일, "Kinematics of paleo-earthquake ruptures based on geomorphic offset analysis using drone-derived topographic data : case studies on strike-slip faults" 60 (60): 37-50, 2024
• 12 Kim, Y. -S., "Interpretation of the rupture history of a low slip-rate active fault by analysis of progressive displacement accumulation : An example from the Quaternary Eupcheon Fault, SE Korea" 168 : 273-288, 2011
• 13 Kim, K. Y., "Gravimetric and magnetic studies in an Yangsan fault area near Angang" 1 (1): 31-40, 1998
• 14 하상민 ; 천영범 ; 강희철 ; 김종선 ; 이선갑 ; 손문, "Geometry and kinematics of the subsidiary faults of the Ilgwang fault, SE Korea" 52 (52): 31-50, 2016
• 15 김태형 ; 최진혁 ; 이호일 ; 배한경 ; 최이레 ; 이태호 ; 천영범 ; 김창민 ; 김동은 ; 류충렬, "First detection of stratigraphic records of paleoearthquakes in Chungbuk Region, Korea" 58 : 411-425, 2023
• 16 Kim, G., "Dipole-dipole array geoelectric survey for fracture zone detection" 2 (2): 217-224, 1999
• 17 Kim, J. H., "DC3DPRO – 3D geoelectrical modelling and inversion. User’s Manual" Korean Institute of Geoscience and Mineral Resources 21-, 2010
• 18 Kim, J. H., "DC2DPro – 2D interpretation system of DC resistivity tomography. User’s Manual and Theory" Korean Institute of Geoscience and Mineral Resources 20-, 2009
• 19 박삼규 ; 천영범 ; 이명종 ; 선창완, "Application of electrical resistivity surveys to detect buried active fault : a case study of the southern Yangsan Fault, Korea" 28 (28): 647-657, 2024
• 20 Park, S., "Applicability of electrical resistivity surveys for tracing and characterizing active fault : a case study in the northern Gongju fault zone, Korea" 2025
• 21 Okada, A., "Active fault topography and trench survey in the central part of the Yangsan fault, south Korea" 103 : 111-126, 1994
• 22 Okada, A., "Active fault topography and fault outcrops in the central part of the Ulsan fault system, southeast Korea" 107 : 644-658, 1998
• 23 Lee, K., "Active Faults of the Southern Korean Peninsula, The National Academy of Sciences" 61 (61): 83-117, 2022
• 24 권오상 ; 박기웅 ; NAIK SAMBIT PRASANAJIT ; 신현조 ; 김영석, "A study on the characteristics of fault activity in the southern part of the Ulsan fault using paleoseismic method" 57 (57): 109-121, 2021
• 25 Lee, K., "A study of microearthquake activity of the Yangsan fault" 19 (19): 127-135, 1983
• 26 Song, S. Y., "4D interpretation of time-lapse electrical resistivity monitoring data to identify preferential flow path in a landfill, South Korea" 195 (195): 1-26, 2023