Collaborative Research: Seismological and Geodynamic Investigations of Mantle Anisotropy

该项目将评估全球地震学和地球动力学模型的稳健性、分辨率和所需的复杂性，以提高我们对地幔动力学的理解。近年来，各向异性的地震学模型得到了改进，推测表明地幔流动发生了剪切作用。尤其是面波反演已与地幔环流模型联系起来，并取得了一些成功。这些发现使得在不久的将来使用复杂的合成数据集测试区域构造模型的假设似乎是可行的。然而，尽管关于各向异性影响的几个问题仍然没有答案，但也确实缺乏全面和量化的模型来彻底估计不确定性。该项目涉及地震学分析和改进的地球动力学模型的一些相关问题，例如：方位各向异性模式在数据选择和反演方法方面的稳定性如何？各向异性在大陆和海洋区域的约束程度如何？对流模型的特点是什么，从牛顿流变学到幂定律流变学，从横向恒定到可变粘度，从有限应变到纹理建模。将进行一系列分辨率和合成模型试验，以评估地震模型的稳健性。这种地震学和地球动力学相结合的研究计划将导致对上地幔结构、各向异性形成和地幔对流的新见解。其目的是使我们对基于地幔流动的岩石圈和上地幔变形的理解形式化，以便开发具有特定区域预测的模型，这些模型有助于野外活动的设计和地质假设检验。

This project will evaluate the robustness, resolution, and required complexity of global seismologic and geodynamic models of upper mantle azimuthal anisotropy in order to improve our understanding of mantle dynamics. Recent years have seen a refinement of seismological models of anisotropy, presumably indicative of shearing in mantle flow. Particularly surface wave inversions have been linked to models of mantle circulation with some success. Such findings make it appear feasible to test hypotheses for regional tectonic models using sophisticated synthetic data sets in the near future. However, while several questions about the implications of anisotropy remain unanswered, it is also true that comprehensive and quantitative models with thorough estimates of uncertainties are still lacking. This project addresses some of the relevant issues of seismological analysis and improved geodynamic models, such as: How stable are azimuthal anisotropy patterns with respect to data selection and inversion methods? How well constrained is anisotropy under continents and oceanic regions? What are the characteristic to convection models, from Newtonian to power-law rheology, from laterally constant to varying viscosity, and from finite strain to texture modeling. A range of resolution and synthetic model tests will be performed to evaluate the robustness of the seismological models. Such a combined seismologic and geodynamic research program will lead to new insights into upper mantle structure, anisotropy formation, and mantle convection. The aim is to formalize our understanding of lithospheric and upper mantle deformation based on mantle flow, in order to develop models with specific regional predictions that are useful for the design of field campaigns and geologic hypothesis testing.