Economic and Environmental Geology (자원환경지질)

The Korean Society of Economic and Environmental Geology (대한자원환경지질학회)
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A Study on Detailed Bathymetry and Geophysical Characteristics of the Summit of the Dokdo Volcano

독도 화산체 정상부해역의 정밀해저지형 및 지구물리학적 특성 연구

  • Kim, Chang Hwan (Dokdo research center, East Sea Research Institute, Korea institute of Ocean Science and Technology) ;
  • Park, Chan Hong (East Sea Research Institute, Korea institute of Ocean Science and Technology) ;
  • Lee, Myoung Hoon (Dokdo research center, East Sea Research Institute, Korea institute of Ocean Science and Technology) ;
  • Choi, Soon Young (Dokdo research center, East Sea Research Institute, Korea institute of Ocean Science and Technology) ;
  • Jou, Hyeong Tae (Maritime Security Research Center, Korea institute of Ocean Science and Technology)
  • 김창환 (한국해양과학기술원 동해연구소 독도전문연구센터) ;
  • 박찬홍 (한국해양과학기술원 동해연구소) ;
  • 이명훈 (한국해양과학기술원 동해연구소 독도전문연구센터) ;
  • 최순영 (한국해양과학기술원 동해연구소 독도전문연구센터) ;
  • 주형태 (한국해양과학기술원 해양방위센터)
  • Received : 2012.09.27
  • Accepted : 2012.12.20
  • Published : 2012.12.28
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Abstract

We studied the detailed bathymetry and the geophysical characteristics of the summit of the Dokdo volcano using mutibeam echosounding and geophysical survey data. The bathymetry around the main east and west islets of the Dokdo volcano shows very shallow within about 10 m water depth. From near islets to about 30 m b.s.l., the shallow water area has very steep slope and many irregular sunken rocks. The area from about 30 m to about 80 m b.s.l. shows gentle rises and falls, and less steep slope. The area from 80 m b.s.l. has gradually flat undulation and smooth slope seabaed and is extended to offshore. The main islets of the Dokdo volcano and the rocky sea bottom elongated from the islets might be the residual part of the eroded and collapsed main crater of the Dokdo volcano. The bathymetry and the seafloor image(from backscattering) data show small craters, assumed to be formed by the eruption of later volcanism. The seafloor images propose that, except some areas with shallow sand sedimentary deposits, there are typical rocky bottom such as rocky protrusions and lack of sediments in the main morphology of the survey area. The stepped slopes of the seabed are deduced to be submarine terraces. The several prominent submarine terraces are found at the summit of the Dokdo volcano, suggesting repetition of sea level changes(transgressions and regressions) in the Quaternary. The results of the magnetic anomaly and the analytic signal have a good coherence with other geophysical consequences regarding to the location of the residual crater.

본 연구는 현재까지 수행된 독도 화산체 정상부 해역의 정밀수심 및 지구물리 조사 자료를 종합하고 분석하여 정상부 해역의 정밀해저지형 및 지구물리학적 특성을 연구하였다. 독도 연안역 동도와 서도 사이 연결 수로는 약 10 m 이내의 얕은 수심을 이루고 있다. 독도 화산체 정상부해역의 전체적인 수심은 동도와 서도의 육지부부터 수면 아래 약 30 m 까지는 불규칙하며 급한 경사면을 가지고, 그 후 수심 약 30 m부터 수심 약 80 m 까지는 경사가 점차 낮아지다가 수심 약 80 m 이하로 완만한 경사를 보이면서 외해역으로 깊어진다. 독도 육지부와 그 북동쪽 및 북서쪽으로 연장되는 암반들은 독도를 생성시킨 화구륜의 잔해로 판단되며 동도와 서도는 화구륜의 남쪽 한부분일 가능성이 큰 것으로 생각된다. 또한 정상부 해역의 해저지형에서는 소규모의 움푹 패인 지형들이 나타나는데 이는 독도 형성 후 나중에 생성된 소규모 분화구의 흔적들로 추정된다. 독도 정상부 해역은 주로 암반이 많이 분포하지만 곳곳에서는 모래 퇴적층들도 나타나는 것을 볼 수 있다. 독도 화산체 정상부에는 계단형의 경사면들이 나타나는데 이는 제4 기에 나타난 해침, 해퇴 등 해수면변화에 의해 만들어진 해저단구로 유추되며, 지역별로 차이가 있기는 하지만 주로 약 30 m, 60 m, 80 m 및 약 100 m의 수심대를 위주로 하여 몇 개의 주요 해저단구가 나타나는 것으로 판단된다. 자기이상도 및 아날니틱신호도를 살펴보면 수면 위 독도에서 연장되는 북동 및 북서쪽의 이상대들은 화구륜의 잔해로 예상되는 암반들의 위치와 유사하게 나타난다.

Keywords

References

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