Extracting Seismic Core Phases with Array Interferometry

用阵列干涉法提取地震核心相位

• 批准号: 1316348
• 负责人: Victor Tsai
• 金额: $ 29.6万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1316348&HistoricalAwards=false
• 关键词: Extracting; Seismic; Core; Phases; Array

Methods that make use of seismic interferometry and ambient noise energy have proven to be extremely useful in imaging shallow Earth structure. Since application of such ambient noise techniques is not limited to where earthquakes occur, if the techniques could be applied to the deep Earth then we would drastically increase our ability to sample the deep Earth. While most studies using ambient seismic noise have failed to retrieve deep body-wave phases, new work of ours suggests that cross correlating body-wave coda emitted by large earthquakes combined with appropriate stacking of array data allows extraction of seismic phases that reflect off the Earth's core and that travel through the Earth's inner core. Currently, however, we do not fully understand why the technique works or what the limitations are. We will develop this ambient-noise/earthquake-coda core-imaging technique more fully, including understanding the basis for the method, improving the process, and applying it to interesting datasets. Promising areas of application include imaging inner core anisotropy, core mantle boundary topography, and deep mantle structure. The fundamental purpose of this work is to develop a new method of imaging the deep Earth that relies on low-amplitude but coherent waves that are part of Earth's ambient noise field. Successful application of the imaging method will provide detailed constraints on how the Earth's core has evolved, on the composition of the deep Earth, and on Earth processes in general. Our line of research will also enable us to assess the full potential of this technique to advance current imaging capabilities in the Earth sciences, but also medical imaging, and oil and gas exploration. Finally, since a crucial aspect of the method is its reliance on waves that take unusual paths, including being scattered and multiply reflected by Earth structure, understanding the method will provide new insight into the heterogeneity of Earth structure and other aspects of the Earth that cause unusual wave propagation.

使用地震干涉法和环境噪声能量的方法已被证明在成像浅层结构中非常有用。 由于这种环境噪声技术的应用不限于发生地震的地方，如果可以将这些技术应用于深层地球，那么我们将大大提高我们采样深层地球的能力。 尽管使用环境地震噪声的大多数研究都无法检索深层的身体波阶段，但我们的新工作表明，大地震发出的交叉相关的人体波尾卷与适当的阵列数据相结合，可以提取地震阶段，从而提取反射地球核心的地震阶段，并穿过地球内核。 但是，目前，我们尚不完全理解该技术为何有效或限制是什么。 我们将更全面地开发这种环境噪声/地震-CODA核心成像技术，包括了解该方法的基础，改进过程并将其应用于有趣的数据集。 有希望的应用领域包括成像内核各向异性，核心地幔边界形象和深幔结构。 这项工作的基本目的是开发一种新的方法来成像深层地球，该方法依赖于低振幅，但连贯的波浪是地球环境噪声场的一部分。 成像方法的成功应用将对地球核心如何发展，深地球的组成以及一般地球过程提供详细的约束。 我们的研究线还将使我们能够评估该技术的全部潜力，以提高地球科学中的当前成像能力，以及医学成像以及石油和天然气勘探。 最后，由于该方法的关键方面是它依赖于采用异常路径的波，包括分散并通过地球结构反射，理解该方法将为地球结构的异质性和地球其他方面的异质性提供新的见解，而地球的其他方面则引起了不寻常的波传播。