Seismic Signatures of Inner Core Solidification

地震波揭示的地球内部深处影响着我们星球表面的过程。其中之一是地球内核从外核的液态铁凝固而成。从地震波中检测到的这种凝固的变化将有助于理解和预测我们磁场的变化，这些变化可能会影响我们的大气层和地表生命。该项目旨在利用地球内核反射和传播的地震波绘制地球内核固化的情况，将向研究生提供计算、数字数据检索和处理以及任何波动现象的结构成像方面的教育和培训。 这些技能可以转移到科学和工程的广泛领域，包括资源勘探，计算科学和医学成像。结果将被纳入本科入门课程，以鼓励跨STEM领域的学生的招聘和保留。研究结果也将定期与对地震和行星科学感兴趣的公众媒体分享。内核边界（ICB）下弹性结构的转变，包括它们对弹性波速度横向变化、体波波形复杂性和衰减以及弹性各向异性的深度起始的影响，对于理解组分对流过程非常重要。这个过程一直被认为是目前维持我们磁场的机制，通过结晶和轻元素在内核固化时的浮力上升。拟议活动的独特要素包括分离地震源对波形的影响，以改善内核衰减的估计，通过前向散射和固有衰减评估衰减的相对贡献，将小尺度不均匀性与固化结构和弹性各向异性联系起来，以及利用对内核边界下的剪切速度结构具有高灵敏度的体波。

The deep interior of Earth, revealed by seismic waves, affects processes at the surface of our planet. Among these is the solidification of Earth's inner core from the liquid iron of its outer core. Variations in this solidification, detected from seismic waves, will be helpful in understanding and predicting variations in our magnetic field that can affect our atmosphere and surface life. This project seeks to map the solidification of Earth's inner core using seismic waves reflected and transmitted through it. Education and training will be provided to graduate students in computation, digital data retrieval and processing, and structural imaging from any wave-like phenomena. These skills are transferable to broad areas of science and engineering, including resource exploration, computational science, and medical imaging. Results will be incorporated in undergraduate introductory courses to encourage recruitment and retention of students across STEM fields. Results will also be regularly shared with public media having interests in earthquakes and planetary science.Transitions in the elastic structure beneath the Inner Core Boundary (ICB), including their effects on lateral variations in elastic waves speeds, body waveform complexity and attenuation and the depth onset of elastic anisotropy are important for understanding the process of compositional convection. This process has been favored as the mechanism that currently sustains our magnetic field through the crystallization and the buoyant rise of light elements as the inner core solidifies. Unique elements of the proposed activity include separating the effect of earthquake sources on waveforms to improve estimates of inner core attenuation, evaluating the relative contributions of attenuation by forward scattering and intrinsic attenuation, relating small- scale heterogeneity to a solidification fabric and elastic anisotropy, and exploiting the use of a body wave having high sensitivity to the shear velocity structure beneath the inner core boundary.