CMG Collaborative Research: Development and Application of Inference Methods for Imaging Neighborhoods of Earth's Core-Mantle Boundary with Broad-Band Scs and SKKS Coda Waves

CMG 合作研究：利用宽带 Scs 和 SKKS 尾波成像地球核幔边界邻域的推理方法的开发和应用

• 批准号: 0417891
• 负责人: Robert van der Hilst
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-15 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0417891&HistoricalAwards=false
• 关键词: CMG; Collaborative; Research; Development; Application

The investigators propose a quantitative, multi-disciplinary investigation of Earth's core mantle boundary, the remote interface between Earth's solid silicate mantle and its liquid iron-alloy outer core. With innovative techniques for interpreting (very) large amounts of broad-band waveform data - obtained from dense networks of seismograph stations - they aim to map, characterize, and interpret multi-scale variations in acousto-elastic properties at and near interfaces in Earth's deep interior. Initially, the team focuses on the physical shell that encompasses Earth's lowermost mantle, the core mantle boundary (CMB), and the outermost core. They will (1) investigate inverse scattering theory based on microlocal analysis making use of generalized Fourier integral operators (GFIOs), (2) develop statistical models based onsuch operators, and (3) apply the new techniques to a large number (millions) of seismogram windows containing waves that reflect at the top (ScS) and underside (SKKS) of the CMB. From a mathematicalsciences perspective, the anticipated result is a generalized Radon transform (GRT) that can generate common image point gathers (IGs) from large data volumes. The IGs are used to (i) detect and determinethe depth to elasticity contrasts (singularities), (ii) determine the regularity of the singularities, and (iii) study characteristic length scales of variations in the inferred parameters. Novel statisticalmethods will be used to enhance the S/N in the transforms, glean more information from the IGs, and provide uncertainty estimates. The geosciences motivation is to use these gathers to improve theunderstanding of (i) the contact between high-viscous mantle and liquid core, (ii) the effect of convective flow on the D'' structure and the character of the CMB, and (iii) outer core heterogeneity (ifany) and its relationship to outer core magneto-hydrodynamics. The collaboration will not only contribute to our general understanding of the composition and phase chemistry of the deep mantle and outermostcore, core-mantle transitions and interactions, and planetary formation. It also offers a unique educational experience for the students, postdocs, and senior staff involved. Indeed, the investigators believe that educating students in geophysics with strong background in mathematicsis important for the future development of the field.

研究人员提出对地核地幔边界进行定量、多学科研究，地核边界是地球固体硅酸盐地幔与其液态铁合金外核之间的远程界面。利用创新技术来解释从密集的地震台网络中获得的（非常）大量宽带波形数据，他们的目标是绘制、表征和解释地球深处界面及其附近声弹性特性的多尺度变化。内部的。最初，该团队关注的是包含地球最下地幔、地幔核心边界 (CMB) 和最外层地核的物理外壳。他们将（1）利用广义傅立叶积分算子（GFIO）研究基于微局域分析的逆散射理论，（2）开发基于此类算子的统计模型，以及（3）将新技术应用于大量（数百万）包含在 CMB 顶部 (ScS) 和底部 (SKKS) 反射的波的地震图窗口。从数学科学的角度来看，预期的结果是广义拉东变换（GRT），它可以从大量数据中生成公共图像点集合（IG）。 IG 用于 (i) 检测和确定弹性对比（奇点）的深度，(ii) 确定奇点的规律性，以及 (iii) 研究推断参数变化的特征长度尺度。新的统计方法将用于增强变换中的信噪比，从 IG 中收集更多信息，并提供不确定性估计。地球科学的动机是利用这些数据来增进对以下方面的理解：(i) 高粘性地幔与液体核心之间的接触，(ii) 对流对 D'' 结构和 CMB 特征的影响，以及 (iii) ）外核异质性（ifany）及其与外核磁流体动力学的关系。此次合作不仅有助于我们对深部地幔和最外核的组成和相化学、核-地幔转变和相互作用以及行星形成的总体理解。它还为相关学生、博士后和高级职员提供独特的教育体验。事实上，研究人员认为，对具有深厚数学背景的地球物理学学生进行教育对于该领域的未来发展非常重要。