Journal of the Korean Geophysical Society (지구물리)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
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AVO Analysis on Gas Hydrates in the Continental Margin off the South shetland Islands, Antarctica

남극 남쉐틀랜드 군도 대륙주변부의 가스수화물 AVO 반응분석

  • 구경모 (한국해양연구원 부설 극지연구소/경북대학교) ;
  • 홍종국 (한국해양연구원 부설 극지연구소) ;
  • 진영근 (한국해양연구원 부설 극지연구소) ;
  • 박민규 (한국해양연구원 부설 극지연구소) ;
  • 남상헌 (한국해양연구원 부설 극지연구소) ;
  • 이정모 (경북대학교)
  • Published : 20060000
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Abstract

Geophysical survey has been conducted on the continental margin off the South Shetland Islands aboard R/V Onnuri of KORDI in 1992/1993. About 800-line km of 96-channel reflection data have been acquired. On the seismic section, BSR with strong reflectivity and negative polarity has been found at 700 ms below the sea bottom. BSR is considered as the base of gas hydrates and AVO analysis was performed to study physical properties along BSR. True amplitude recovery and surface consistence amplitude were applied to seismic data and angle gathers were obtained. AVO gradient and AVO intercept are calculated on every CDP gather. Section of AVO intercept show strong reflectivity and negative polarity on BSRs and stronger continuity of BSR than stacked section. Cross plot of P-G indicates that the lower layer below BSR is filled with free gas.

1993년 남극 하계 기간 동안 남쉐틀랜드 대륙주변부에서 한국해양연구원의 종합연구선 온누리호를 이용하여 탄성파 탐사를 실시하였으며 약 800 km의 탄성파자료를 획득하였다. 탄성파 자료에서 음의 반사계수를 보이며 상대적으로 강한 진폭을 갖는 BSR이 해저면 700 ms에서 발견되었으며 이는 가스수화물의 기저면으로 간주된다. BSR 경계면에서의 물성을 밝히기 위하여 AVO 분석을 수행하였다. 탄성파 자료에 대하여 실진폭 회수, surface consistence amplitude 보정, 입사각 변환 등을 수행하고, 각각의 CDP 자료에 대하여 AVO 절편 및 AVO 기울기를 구하였다. AVO 절편의 단면도는 BSR 경계면에서 극성이 음이고 강한 반사도를 보이며 중합단면도보다 BSR 경계면의 연속성이 뚜렷하였다. AVO 분석자료를 P-G 도면으로 표시한 결과, BSR이 뚜렷한 곳의 하부에는 가스로 채워졌음을 시사한다.

Keywords

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