| 講演要旨(和文) | | 海底活断層調査の技術的な信頼度を向上させていくため,以下の4項目に取り組んだ.1)日本列島沿岸海域における海底地質情報の総括とデータベース化.2)海底活断層調査の技術的現状と活動性評価手法の検証.3)海底に分布する断層関連褶曲に対する活動性評価手法の検討.4)海底に分布する横ずれ断層に対する活動性評価手法の検討.その結果,以下の知見を得た.1)日本列島周辺の既存の海底地質情報では,深度1000 メートル程度の地質構造を網羅的に概観できる. 2)現状の海底活断層調査結果に基づく活動性評価は,断層を被覆する堆積層の年代がわかれば,陸域と同じレベルである.3)長い褶曲構造も,形態的には区分できる.活褶曲のセグメンテーションは,震源断層の活動にともなう変形が顕著に累積する区間を示す.4)一つの断層グループに属する雁行する横ずれ断層は,フラワーストラクチャー全体を評価することが重要である. |
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| | 講演要旨(英文) | | Based on the existing state and problems of submarine active fault investigation in the coastal region, we examined four subjects to improve the reliability of submarine active fault evaluation. We obtained the result described below. (1) We can grasp the geological structure around the Japanese Islands comprehensively to 1000m under the seabed using the existing submarine geological information. However, the detailed age information about marine sediment is insufficient. (2) When the age of the deposition layer which covers fault has been grasped, the level of fault activity evaluation based on the present submarine active fault investigation is the same level as the case of land. (3) Long fold in topography as well as an active fault can be divided morphologically to a short segment. However, the segmentation of fold shows the section which deformation of the stratum accompanying the displacement of earthquake source fault accumulates notably. The activity section of earthquake source fault itself is not shown. (4) When many submarine strike-slip faults which go side by side are distributed over the seabed, it is the most important subjects for activity evaluation of them to grasp the subsurface structural forms like the flower structure typical of them. |
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