地震アニソトロピーに基づく地球のマントルの底辺の流れに関する推論
Mark Panning1, Barbara Romanowicz
1Berkeley Seismological Laboratory, 215 McCone Hall, University of California, Berkeley, CA 94720, USA. mpanning@seismo.berkeley.edu
まとめ
グローバル波形トモグラフィーでは,マントル全体で放射性アニソトロピーを明らかにしています. コア・マントル境界付近では,水平に偏ったS波速度 (VSH) は,垂直に偏ったS波速度 (VSV) よりも速く,水平切断を示し,D"領域を機械的境界層として確認します.
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
- 地球科学 地球科学 地球科学
背景:
- マントルのダイナミクスを理解することは,プレート構造と地球の熱的進化を理解するために不可欠です.
- 地震波の速度における放射性アニソトロピーは,マントルの流れと変形についての洞察を提供します.
- コアとマントルの境界にあるD"領域は,マントルとコアの相互作用を研究するための重要な領域です.
研究 の 目的:
- 地球のマントル全体を通して放射性アニソトロピーをモデル化するために.
- D"領域内の機械的性質と流動パターンを調査する.
- スーパープルームのような大規模なマントル構造と関連した地震シグネチャーを特定する.
主な方法:
- グローバル波形トモグラフィの応用.
- 地震波の速度,特に水平偏振S波 (VSH) と垂直偏振S波 (VSV) の速度を分析する.
- マントル全体における放射性アニソトロピーのモデリング.
主要な成果:
- D"領域では,VSH速度がVSV速度よりも約1%速く,横断切断の大規模な優位性が検出されました.
- D"領域は,マントルのコンベクションのための機械的境界層として確認されています.
- 太平洋とアフリカのスーパープルームの下にあるアニゾトロプ的パターンは,平均的な水平切断シグネチャーから逸脱する垂直フローの発生を示唆しています.
結論:
- D"領域は,水平切断の兆候であり,機械的境界層としての役割を示す,有意な放射性アニソトロピーを示しています.
- 地震アニソトロピーは,スーパープルームに関連した垂直流を含む下層マントルの内部で明確な流れ体制の証拠を提供します.
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