地球のマントルの圧縮波速度に対する相変化の影響
1Mineral Physics Institute Department of Geosciences, Stony Brook University, Stony Brook, New York 11794, USA. lilli@ic.sunysb.edu
Nature
|August 23, 2008
まとめ
地球における地震波の速度
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- ミネラル物理学 ミネラル物理学
- 地震学 地震学とは
背景:
- 地震波の速度は,圧力とストレスに対する鉱物の反応に依存する.
- ボリュームを減らすフェーズ変換により,ボリュームモジュールが大幅に低下します.
- 地球の深いところでの実験データを得ることは困難です.
研究 の 目的:
- 段階移行中の地震波の速度変化を実験的に調査する.
- 波の伝播に対する相変化運動の影響を評価する.
- 段階移行が地球のマントルの地震速度に影響するかどうかを判断する.
主な方法:
- シンクロトロンベースのX線 difrraction実験が行われました.
- オリヴィン-リングウッド酸塩の相移行が研究されました.
- バルクモジュールの軟化率は,100秒のタイムスケールで測定されました.
主要な成果:
- オリヴィン-リングウッド酸二相ループの内部で,バルクモジュール軟化が観察されました.
- 圧縮波の速度は,地球の410キロ,520キロ,660キロの不連続点では低い可能性が高い.
- 結果は,予想される地球の圧力と粒子のサイズにスケーリングされた.
結論:
- フェーズトランジション運動は,地震波の速度に大きな影響を与えます.
- この発見は,上層マントルの実質的な速度乱れを示唆しています.
- 似たような効果は,他の相変化でも起こり,マントルの構造モデルに影響を与える可能性があります.
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