Seismic Signatures of Inner Core Solidification

地震波揭示的地球内部深处，影响着地球表面的活动。其中之一就是地球内核由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磁场的变化，而磁场的变化可能会影响我们的大气和地表生命。这个项目试图通过反射和透射的地震波来绘制地球内核的凝固情况。为研究生提供计算、数字数据检索和处理以及任何波状现象的结构成像方面的教育和培训。这些技能可以转移到广泛的科学和工程领域，包括资源勘探、计算科学和医学成像。结果将纳入本科入门课程，以鼓励在STEM领域招收和留住学生。研究结果也将定期与对地震和行星科学感兴趣的公共媒体分享。内核边界下弹性结构的转换，包括它们对弹性波速度的横向变化、体波的复杂性和衰减以及弹性各向异性的深度开始的影响，对理解成分对流过程具有重要意义。这个过程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。提出的活动的独特元素包括分离震源对波形的影响，以改进对内核衰减的估计，通过前向散射和本征衰减评估衰减的相对贡献，将小尺度非均质性与凝固结构和弹性各向异性联系起来，以及利用对内核边界下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.