Geodynamically relevant anisotropic tomography

地球动力学相关各向异性断层扫描

• 批准号: 0911414
• 负责人: Mark Panning
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911414&HistoricalAwards=false
• 关键词: Geodynamically; relevant; anisotropic; tomography

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Seismic tomography is one of the best tools for imaging the interior structure of the Earth, which is inaccessible by other means. Expanding these models to include anisotropy (i.e. directional dependence) of seismic velocities can more directly image the dynamic processes of the deep Earth. While many tomographic models including seismic anisotropy have been developed, there are few that invert for both strength and orientation of anisotropy in order to allow for direct comparison with geodynamic models, which make predictions about the patterns of mantle convection based upon assumptions of the mantle's viscosity and other rheological properties. The long term goal of this research is to develop global as well as more detailed regional models of seismic anisotropy that can both illuminate the dynamic processes of the mantle, as well as allowing for direct comparison with geodynamically predicted models. The objective of this application, which is the next step towards this long-term goal, is to test and apply a new approach of utilizing 3D finite-frequency modeling of surface wave data to model both the strength and best-fitting orientation of anisotropic seismic structure. We expect that this approach, when combined with finite-frequency modeling of shear wave splitting intensity data, will produce models which allow for direct comparison with geodynamical flow models, as well as allowing for anisotropic modeling of relatively sparse regional data. We plan to demonstrate the potential of this approach by pursuing the following specific aims. (1) Verify that the surface wave modeling method can accurately reproduce known models when applied to a large synthetic dataset calculated with known models of anisotropy. (2) Incorporate shear splitting intensity measurements into the model, expected to be complementary in terms of spatial sensitivity and relative sensitivity to different model parameters. (3) Apply the approach to a dataset from the Chile Ridge Subduction Project. This temporary deployment of broadband seismic instruments sampled a region of tectonic interest between 2004 and 2007, and the modeling of this relatively sparsely sampled region presents both a challenge and an opportunity to demonstrate the strengths of the proposed approach. The proposed work is innovative because it takes advantage of a new method of modeling surface wave data that has just been developed by the PI. This method is expected to allow for direct modeling of the strength and orientation of anisotropy beyond what has been traditionally obtained in anisotropic modeling. This approach is ideally suited for direct comparison with geodynamic predictions, allowing for a unique method of imaging the flow patterns of the Earth's mantle.This work will contribute to advancement of discovery and understanding while promoting teaching, training and learning through the training of at least one Ph.D. student, as well as potentially one or more Masters and undergraduate students, and the incorporation of such projects into class work. It will also supply for the enhancement of infrastructure for research and education, through the optimization of a new HPC cluster that will be used by other research groups. Finally, we expect the broad dissemination of results through presentation at international meetings and peer-reviewed journals. Computer codes developed in this research will be made available through the PI's website.

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。地震层析成像是成像地球内部结构的最好工具之一，这是其他方法无法获得的。将这些模型扩展到包括地震速度的各向异性(即方向相关性)，可以更直接地反映地球深处的动态过程。虽然已经开发了包括地震各向异性在内的许多层析模型，但很少有模型能够同时反转各向异性的强度和方向，以便与地球动力学模型进行直接比较，后者基于对地幔粘度和其他流变性的假设来预测地幔对流模式。这项研究的长期目标是开发全球和更详细的区域地震各向异性模型，既能阐明地幔的动态过程，又能与地球动力学预测模型进行直接比较。这项应用的目标是测试和应用一种新的方法，即利用面波数据的3D有限频率建模来模拟各向异性地震结构的强度和最佳拟合方向。我们预计，当这种方法与剪切波分裂强度数据的有限频率建模相结合时，将产生允许与地球动力学流动模型直接比较的模型，以及允许对相对稀疏的区域数据进行各向异性建模。我们计划通过追求以下具体目标来展示这一方法的潜力。(1)验证了面波模拟方法应用于利用已知各向异性模型计算的大型合成数据集时，能够准确地再现已知模型。(2)在模型中加入剪切劈裂强度测量，期望在空间敏感性和对不同模型参数的相对敏感性方面具有互补性。(3)将该方法应用于智利山脊俯冲项目的数据集。这种宽带地震仪器的临时部署在2004年至2007年期间对一个具有构造意义的地区进行了抽样，对这个相对稀少的抽样地区的建模既是一个挑战，也是一个展示拟议方法优势的机会。提出的工作具有创新性，因为它利用了PI刚刚开发的一种新的面波数据建模方法。这种方法有望允许对各向异性的强度和取向进行直接建模，而不是传统上在各向异性建模中获得的。这一方法非常适合于与地球动力学预测进行直接比较，从而提供了一种成像地球地幔流动模式的独特方法。这项工作将有助于促进发现和理解的进步，同时通过培训至少一名博士生，可能还有一名或多名硕士和本科生，并将这些项目纳入课堂工作来促进教学、培训和学习。它还将通过优化将由其他研究小组使用的新的高性能计算集群，为加强研究和教育的基础设施提供资金。最后，我们期望通过在国际会议和同行评议期刊上的介绍来广泛传播成果。在这项研究中开发的计算机代码将通过PI的网站提供。