中央太平洋下にあるマントルの底辺にある3次元構造
1Seismological Laboratory, University of California, Berkeley, CA 94720, USA.
まとめ
地震波の分析により,太平洋の下部で予期せぬ地幔構造が明らかになった. 大きな熱い羽根と顕著な高速のS速度帯は,複雑な地球深層のダイナミクスを示唆しています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 地震学 地震学とは
- 地球の奥深くにある内部.
背景:
- トモグラフィックモデルは,地球のマントルの構造の概観を提供します.
- 地震波の伝播を理解することは,地球の深部をイメージするための鍵です.
- 最下層マントルとコアマントルの境界は,熱と物質の交換のための重要な領域です.
研究 の 目的:
- 太平洋中部下部の最下層マントルの地震速度の異常を調査する.
- フォワードモデリングの結果を既存の地震トモグラフィーと比較する.
- 観測された地震異質性の性質と影響を解釈する.
主な方法:
- 地震差分移動時間の前向きモデリング.
- 最下層マントルに対して敏感な地震相の分析.
- モデル予測と観測データを比較する.
主要な成果:
- トモグラフィーモデルによって予測されたより高い振幅を持つ横向的な異質性を特定しました.
- 低S速度 (−4%) の広いゾーンが検出され,潜在的に熱い羽根のベースが狭くなり,上向きに傾斜しています.
- 東に高速なS速度 (+5%) の局所的な領域が観察され,強力な異質性またはアニソトロピーを示し,おそらく高圧/高温組立物またはコア材料に関連している.
結論:
- 太平洋中部下の最下層のマントルは,現在のトモグラフィックモデルによって完全に捉えられない重要な地震異質性を表しています.
- 発見は,深い熱い羽根と,コア-マントルの境界付近の異常な物質または構造の明確な領域の存在を示唆しています.
- 急速なS速度領域は,コア反射相の地震観測に影響を与え,コア-マントルの相互作用の洞察を提供します.
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