在地球上层地幔中,失位缓和和异型地震波衰减
Robert J M Farla1, Ian Jackson, John D Fitz Gerald
1Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia. robert.farla@yale.edu
Science (New York, N.Y.)
|April 21, 2012
概括
晶体缺陷,称为失位,可能会抑制地震波. 实验室实验表明,预先变形的橄石表现出增强的波浪散射,这表明地球上层地幔的异型地震减弱.
科学领域:
- 地质物理学 地质物理学
- 固体地球地质物理学 地质物理学
- 矿物物理 矿物物理
背景情况:
- 晶体缺陷,特别是失位,在构造变形过程中形成.
- 这些失位可能会导致上层地幔的地震波减弱.
- 之前的实验室证据表明,位缓解是间接的.
研究的目的:
- 为了实验性地确定在预变形的橄中剪切模量和应变能量消散.
- 为了研究失位在地震波衰减中的作用.
- 评估先前变形 (压缩与扭曲) 对消散的影响.
主要方法:
- 切削模量和应变能量消散的实验性确定.
- 使用经过高压和高温的合成橄烯聚合物.
- 使用预变形技术 (压缩和扭曲) 来引入位移.
主要成果:
- 在预变形的橄中观察到增强的高温背景消散.
- 与压缩相比,通过扭动预先变形的标本中,分散增强的程度更大.
- 结果表明,离位密度/类型和地震波衰减之间存在联系.
结论:
- 位爬行在olivine显著影响地震波消散.
- 在上层地幔中,由于olivine变形,可能存在异型地震减弱.
- 这些发现支持晶体缺陷在调节地震波传播中的作用.
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