Collaborative Research: The impact of time-dependent mantle rheology and 3-D structure on models and observations of Glacial Isostatic Adjustment

地幔黏度在地球的长期演化中起着重要作用，它控制着地球内部的冷却、地幔的对流（推动板块构造）以及地球旋转轴的稳定性。地幔粘度的知识对于模拟地球的长期变化也是至关重要的。这种形状被称为冰川均衡调整，或冰期后反弹。这些变化与地球有关吗？美国冰期旋回，以及对地幔黏度的准确估计似乎是解决气候研究中一些正在进行的争论的关键。然而，我们对地幔粘度的了解是高度不确定的，因为地球？S的内部不能直接观测，只能通过对其表面的观测间接探测。我们在这方面最有用的两个工具是地震学和大地测量学，前者提供了关于地球内部重要物质边界的高分辨率信息，后者提供了关于冰川后反弹的观测，如地壳变形、海平面和重力的变化以及地球的变化。S自转轴。该项目将结合地震模型和大地测量观测来估计地球模型的参数，包括成分、温度、熔化程度以及其他热力学和成分参数。通过同时使用地震模型和大地测量观测，该项目可以潜在地利用两种观测技术的最佳分辨率和灵敏度来确定一个模型，在拟合两种观测类型的意义上是统一的。在这个项目中要解决的主要问题是这种方法的可行性如何（就约束地球模型的多个参数的能力而言）。除了最先进的地震和大地测量信息外，该项目还将采用最近开发的方法来计算与地球物理学相关的广泛时间尺度上的流变特性，从地震波频率到与板块构造相关的应变率。这项研究将导致基于地震模型的地幔流变参数的初步三维模型，以及与冰川后反弹相关的变形、重力和海平面变化的一致估计；这将有助于我们更好地了解地幔对流和长期气候变化对固体地球的影响。

Mantle viscosity plays a fundamental role in the long-term evolution of Earth, controlling cooling of its interior, convective flow in its mantle (which drives plate tectonics), and the stability of its rotation axis. Knowledge of mantle viscosity is also crucial for modeling the long-term changes in Earth?s shape known as Glacial Isostatic Adjustment, or postglacial rebound. These changes are associated with Earth?s glacial cycles, and accurate estimates of mantle viscosity appear to be key to resolving a number of ongoing debates in climate research. Our knowledge of the viscosity of the mantle, though, is highly uncertain, since Earth?s interior cannot be directly observed, but only probed indirectly through observations at its surface. Two of our most useful tools for this are seismology, which provides high-resolution information regarding important material boundaries in the interior of the Earth, and geodesy, which provides observations relating to postglacial rebound, such as crustal deformation, variations in sea-level and gravity, and changes in Earth?s spin axis.The project will combine seismic models and geodetic observations to estimate parameters of an Earth model that includes composition, temperature, degree of melt, and other thermodynamic and compositional parameters. By using seismological models and geodetic observations simultaneously, the project can potentially take advantage of the best resolving power and sensitivities of both observational techniques to determine a model, unified in the sense of fitting both types of observations. The primary question to be addressed in this project is how feasible (in terms of capability for constraining multiple parameters of the Earth model) such an approach is. Along with state-of-the-art seismic and geodetic information, the project will employ recently developed methodology for calculating rheological properties across the broad spectrum of time scales relevant to geophysics, from seismic wave frequencies to strain rates associated with plate tectonics. This study will lead to preliminary three-dimensional models for mantle rheological parameters based on seismic models, and to consistent estimates of deformation, gravity, and sea level change associated with postglacial rebound; these will lead to an improved understanding of mantle convection and the impact of long-term climate change on the solid Earth.