在中央太平洋下方的地幔底部的三维结构
1Seismological Laboratory, University of California, Berkeley, CA 94720, USA.
概括
地震波分析揭示了太平洋下面意想不到的下层地幔结构. 一个巨大的热和一个明显的快速S-速度区域表明了复杂的地球深层动态.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 地球的内心深处是地球的深处.
背景情况:
- 断层模型提供了地球地幔结构的一般视图.
- 了解地震波传播是绘制地球深层图像的关键.
- 最下层地幔和核心地幔边界是热量和物质交换的关键区域.
研究的目的:
- 为了研究太平洋中部下面最下层地幔的地震速度异常.
- 将前建模结果与现有的地震断层扫描进行比较.
- 解释观察到的地震异质性的性质和影响.
主要方法:
- 对地震差异旅行时间的前向建模.
- 对最下层地幔敏感的地震相的分析.
- 模型预测与观测数据的比较.
主要成果:
- 确定了横向异质,幅度高于断层模型预测的幅度.
- 检测到一个低S速度 (-4%) 的广区域,可能是一个热羽根基地,缩小并向上偏移.
- 观察到东部一个局部化的快速S-速度 (+5%),表明强烈的异质性或异质性,可能与高压/高温组合或核心材料有关.
结论:
- 太平洋中部下面的最下层地幔表现出显著的地震异质性,目前的断层模型无法完全捕捉到.
- 这些发现表明存在深层热和核心-地幔边界附近的异常物质或结构的明显区域.
- 快速的S-速度区域可能会影响核心反射相的地震观测,为核心-地幔相互作用提供见解.
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