在加勒比海下方的下层地幔横向异质性
1Department of Geological Sciences, Southern Methodist University, Dallas, TX 75275-0395, USA.
概括
地震波在反射地球核心和最下层地幔时表现出不寻常的缓慢. 这些异常表明下层地幔的速度结构具有显著的横向变化,与标准地球模型有所不同.
科学领域:
- 地质物理学 地质物理学
- 地震学 地震学
- 地球科学 地球科学 地球科学
背景情况:
- 地震波传播被用来推断地球的深层结构.
- 该IASPEI91模型是地震波旅行时间的标准参考.
- 异常的地震波行为可以表明与预期的地球模型的偏差.
研究的目的:
- 为了研究从特定地区观察到的地震波缓慢异常.
- 为了确定与IASPEI91标准地球模型观察到的偏差的原因.
主要方法:
- 来自地球核心的地震波反射的分析.
- 从加勒比海,委内瑞拉和中大西洋山脊的事件记录北美阵列的地震数据.
- 检查P波在最下层的地幔中旋转.
主要成果:
- 观测到的地震波缓慢度超过了IASPEI91模型预测的64%.
- 对于核心反射和最下层地幔P波,都检测到了异常缓慢.
- 这些缓慢异常发生在没有显著的旅行时间残留的情况下.
结论:
- 下地幔速度结构的侧面不均性是观察到的地震缓慢异常的可能原因.
- 这些发现突出了IASPEI91标准地球模型在某些地区的局限性.
- 对下层地幔速度结构的进一步研究是有必要的.
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