| 講演要旨(和文) | | 新潟県上越沖にてSound Oceanics 社の SoundArray 3D System(SA3D)を用いた高精度三次元調査を実施した。本調査は上越沖海域で発達するガスチムニー構造の詳細を明らかにする目的で実施した。また、短いケーブルを用いたSA3Dでは困難な速度解析のために長いケーブルを用いた二次元データも別途取得した。現場記録は、波浪やインダクションなどの強いノイズで反射波がマスクされていたが、複合的なノイズ抑制処理により良好な反射記録を得ることができた。また、ケーブル深度変化などによるフットプリントノイズも除去することによりS/N比の向上をおこなった。このような綿密な処理により得られた高分解能3Dデータを用いたガスチムニー詳細構造の解明が進みつつある。 |
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| | 講演要旨(英文) | | A high-resolution 3D seismic survey with short cables was carried out off Joetsu, Niigata Prefecture, using "SoundArray 3D (SA3D)" System developed by Sound Oceanics, Inc. This survey was conducted to delineate detailed gas chimney structures in which shallow methane hydrates deposit. Additionally 2D lines with a longer cable were also acquired for velocity analysis because SA3D with short cables is not suitable to have accurate velocity structure. The original data were heavily contaminated with swell and induction noises, etc., then a comprehensive noise suppression was applied to eliminate such noises. The footprint noises caused by variation of cable depth and other water column statics were also suppressed to enhance S/N ratio. Thanks to the elaborate processing, a high resolution 3D data volume was obtained and the data have been used to reveal the fine structure of the gas-chimneys and BSR in this region. |
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