Structure and motion of the inner core from dense arrays

核心是位于地球中心的1000公里半径的实心金属球，嵌在液态金属外核中，是一个基本感兴趣和公众着迷的主题。冻结外核以建立内核为地球磁场提供动力，因此内核结构和运动的改进将揭示外核中的对流地球发电机，从而产生波动磁场，这影响了地球的演化并保护了地球上的生命。这个项目将集中几个大型地震仪阵列来成像内核中的精细结构，以努力加深我们对其过程的理解。该奖项将支持研究生和博士后学者，并包括国际合作。地球核心(IC)是一个核心但鲜为人知的前沿。了解它的结构、运动和历史都是一项艰巨的挑战。已经估计了地震速度变化、各向异性、上层各向同性层厚度和衰减的时间变化和大致的半球结构，但到目前为止，对这些观测的解释是不完整的，而且往往是相互矛盾的。研究人员将使用精细的波束形成技术，应用于20世纪70年代来自大口径地震台阵(LASA)、现代Hi-Net和中国台阵(CH台阵)以及几个较小台阵的数据，以探索精细IC异质性的分布。支持者的目标是用密集阵列形成波束，以绘制和表征具有强烈异质性的IC区域，以解释结构和跟踪它们的运动。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The inner core, the 1000-km-radius solid metal ball at the center of Earth embedded in the liquid metal outer core, is a subject of fundamental interest and public fascination. The freezing of the outer core to build the inner core powers Earth’s magnetic field and so refinement of inner core structure and motion will shed light on the convective geodynamo in the outer core and thus the generation of the fluctuating magnetic field, which has affected evolution and protects life on Earth. This project will focus several large arrays of seismometers to image the fine structure in the inner core in an effort to deepen our understanding of its processes. This award will support a graduate student and post doctoral scholar, and includes international collaboration.Earth’s inner core (IC) is a central but poorly understood frontier. Understanding its structure, motion, and history all pose formidable challenges. Temporal changes and roughly hemispherical structure of seismic velocity variation, anisotropy, thickness of the upper isotropic layer, and attenuation have been estimated, yet interpretation of these observations has so far been incomplete and often contradictory. The investigators will use refined beam-forming techniques, applied to 1970s data from the Large Aperture Seismic Array (LASA), the modern Hi-Net and China Arrays (CHArray), and several smaller arrays to explore the distribution of fine-scale IC heterogeneity. The proponents aim to beam-form with dense arrays to map and characterize IC regions with strong heterogeneity to interpret the structures and track their motion.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.