マントルの中間の深さの地震のための周期的な剪定加熱機構です
1Department of Earth and Environmental Sciences, Columbia University, Lamont Doherty Earth Observatory, Palisades, New York 10964, USA. peterk@ldeo.columbia.edu
Nature
|April 13, 2007
まとめ
中程度の深さの地震は,単に脱水ではなく,局所的な粘着性のクリープから発生します. この新しいモデルは,潜水地帯の下の地震活動を説明し,準周期的な不安定なサイクルを明らかにします.
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
- テクトニクス (地質学) とは
背景:
- 中間の深さの地震は,脆性-柔性移行の下の潜水地帯で発生します.
- 現存するモデルでは,熱または脱水メカニズムが示唆されているが,これらは一部の地震発生地には不十分である.
- このような深さでの高圧は,摩擦故障の可能性を低くする.
研究 の 目的:
- 中程度の深さの地震に対する代替メカニズムを提案し,モデリングする.
- 水性鉱物の存在の深さ以下で発生する地震活動を説明するために.
主な方法:
- 粗粒度の弾性半空間内の細粒度の切断ゾーンの数値モデリング.
- オリヴィン流動法則を活用し,剪定加熱効果をシミュレートする.
- 初期温度 (600~800°C) と背景張力率 (10−1210−15s−1) を含む.
主要な成果:
- 局所的粘着性のクリープは,剪定加熱により急速に開始され,張張率と温度が増加します.
- 張力率は1s−1を超え,気温は1,400°Cに達し,その後はストレスの低下が続く.
- このプロセスは,継続的な遠場変形の下で準周期的な地震の不安定性をもたらします.
結論:
- 細粒子の切断地帯における粘着性のクリープは,中程度の深さの地震に有効なメカニズムを提供します.
- このメカニズムは,脱水が可能な場所よりも深く発生する地震を説明します.
- このモデルは,これらの地震の周期的な性質を予測しています.
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