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Fine-scale heterogeneity in the Earth's inner core

机译:地球内核中的精细尺度异质性

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摘要

The seismological properties of the Earth's inner core have become of particular interest as we understand more about its composition and thermal state. Observations of anisotropy and velocity heterogeneity in the inner core are beginning to reveal how it has grown and whether it converts. The attenuation of seismic waves in the inner core is strong, and studies of seismic body waves have found that this high attenuation is consistent with either scattering or intrinsic attenuation. The outermost portion of the inner core has been inferred to possess layering and to be less anisotropic than at greater depths. Here we present observations of seismic waves scattered in the inner core which follow the expected arrival time of the body-wave reflection from the inner-core boundary. The amplitude of these scattered waves can be explained by stiffness variations of 1.2% with a scale length of 2 kilometres across the outermost 300 km of the inner core. These variations might be caused by variations in composition, by pods of partial melt in a mostly solid matrix or by variations in the orientation or strength of seismic anisotropy.
机译:随着我们进一步了解地球的组成和热态,地球内核的地震学特性引起了人们的特别关注。内核中各向异性和速度异质性的观察开始揭示它是如何生长的以及是否转换。内核中地震波的衰减很强,对地震体波的研究发现,这种高衰减与散射或固有衰减一致。已经推断出内芯的最外部具有分层并且与较大深度相比具有较小的各向异性。在这里,我们介绍了在内核中散射的地震波的观测结果,这些地震波遵循从内核边界出发的体波反射的预期到达时间。这些散射波的振幅可以用1.2%的刚度变化来解释,在整个内芯的最外300 km处的标度长度为2 km。这些变化可能是由于成分变化,大部分为固态的部分熔体荚或地震各向异性的方向或强度变化引起的。

著录项

  • 来源
    《Nature》 |2000年第6775期|p.273-275|共3页
  • 作者

    John E. Vidale; Paul S. Earle;

  • 作者单位
  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然科学总论;
  • 关键词

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