Solidification Texture of the Uppermost Inner Core

分析地震波形以确定地球固体内核中小尺度结构变化的空间谱或纹理。 强烈不同的灵敏度的形状和尾波的地震体波入射在近垂直与近水平角的内核边界上的映射横向变化的非均匀纹理的内核。固体内核的结构的横向变化可以记录液体外核底部的流体流动的横向变化，并限制内核的旋转被锁定到地幔旋转的程度。两名研究生参与了这项研究。 具有更广泛影响的研究成果包括地球小尺度不均匀性对地震波形影响的定性和定量规则，以及对地球内核小尺度结构如何与外核流体流动及其与磁场时间变化关系的理解。这项研究的结果是很重要的，以了解如何从液态外核的固体内核的固化维持地球的磁场，以及如何冷却地球的核心耦合到冷却和动态演化的地幔。地球的磁场和冷却历史对地球大气和地表生命的演化都有重要意义。

Seismic waveforms are analyzed to determine the spatial spectrum or texture of small scale structural variations in Earth's solid inner core. Strongly differing sensitivities of the shapes and codas of earthquake body waves incident at near vertical versus near horizontal angles on the inner core boundary are exploited to map lateral variations in the heterogeneous texture of the inner core. Lateral variations in the texture of the solid inner core may record lateral variations in fluid flow at the bottom of the liquid outer core and constrain the extent to which the rotation of the inner core is locked to rotation of the mantle. Two graduate students participate in this study. Research products having a broader impact include qualitative and quantitative rules governing effects of small scale heterogeneity in the earth on seismic waveforms, and an understanding of how small scale structure in the earth's inner core is related to fluid flow in the outer core and its relation to time variations in the magnetic field. Results of this study are important to understanding how the solidification of the solid inner core from the liquid outer core sustains Earth's magnetic field and how the cooling of the Earth's core is coupled to the cooling and dynamic evolution of Earth's mantle. Both the magnetic field and cooling history of Earth are important to the evolution of Earth's atmosphere and surface life.