CAREER: Modification of a Continent: Seismic Tomography and Imaging of the Northern American Lithosphere

大陆岩石圈（地球的固体外壳）的变化可以极大地影响我们星球的表面环境，例如通过控制天气模式和水的流动。了解大陆的变化如何取决于深度过程依赖于地球内部详细的地震图像。由于地震数据覆盖面广，北美是研究不同背景下大陆改造的理想场所。虽然它是最广泛的成像大陆之一，其演变的基本过程的细节仍然难以捉摸，主要是由于现有的地震图像之间的差异。该项目的目标是提高北美岩石圈从地表到根部的地震图像分辨率。将利用先进的地震成像技术和补充地震数据集来开发这些模型，这些数据集可以提供关于大陆岩石圈物理性质和特征的更完整的信息。该项目的成果将有助于了解北美大陆是如何建造、改造和破坏的。该项目将紧密结合研究，教育和公共宣传，通过密集的“斯巴达摇”夏令营和研究为基础的教育计划，为代表性不足的本科生和高中科学教师。该项目还将通过分析、建模和可视化部署在密歇根州立大学校园的Raspberry Shake 3D地震仪收集的环境地震数据，增强参与者的现场科学体验。该项目旨在通过绘制波速和内部界面（包括沉积物基底、莫霍面以及岩石圈和软流圈边界）的三维变化来准确地对北美岩石圈进行成像。随着岩石圈结构地震学约束的增强，可以实现以下三个关键科学目标：（1）了解岩石圈结构的横向梯度如何通过减薄、裂陷、增厚和沉降控制板块边缘的变形;（2）系统研究不同构造环境下软流圈与岩石圈的相互作用;（3）研究沉积盆地和地壳内与岩石圈和软流圈过程相对应的地震特征。将用不同的全波形反演技术同化补充地震数据集，包括环境噪声衍生的经验绿色函数和EarthScope移动式阵列记录的区域数据和地震数据。该项目将在全波形反演框架下提供所有这些数据集的首次联合反演，以便对大陆演变进行更定量的模型比较、评估和解释。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Changes in the continental lithosphere, the solid outer shell of the Earth, can greatly impact the surface environment of our planet, for example by controlling weather patterns and movement of water. Understanding how changes in the continents depend on processes at depth relies on detailed seismic images of the earth’s interior. With great seismic data coverage, North America is a perfect site for studying continental modification in diverse settings. Although it is one of the most extensively imaged continents, the details of the underlying processes of its evolution are still elusive, largely due to the discrepancies between existing seismic images. The goal of this project is to improve the seismic image resolution of the lithosphere of the North America from the surface to its root. The models will be developed using advanced seismic imaging techniques and complementary seismic data sets that can provide more complete information about the physical properties and features of the continental lithosphere. The results of this project will contribute to the understanding of how the North American continent is built, modified and destroyed. This project will tightly integrate research, education, and public outreach through an intensive “Spartan Shake” summer camp and research-based educational plan for under-represented undergraduate students and high-school science teachers. This project will also enhance the onsite science experience of the participants through analyzing, modeling, and visualizing the environmental seismic data collected by Raspberry Shake 3D seismometers deployed on the Michigan State University campus. This project aims at accurately imaging the lithosphere of North America by mapping 3D variations of both wave speeds and the internal interfaces, including sediment base, Moho, and the lithosphere and asthenosphere boundary. With the more robust seismological constraints of lithospheric structures, the following three key scientific goals can be achieved: (1) understand how the lateral gradients of lithospheric structure control the deformation of the plate margins through thinning, rifting, thickening, and foundering; (2) systematically investigate how asthenosphere interacts with lithosphere across different tectonic environments; (3) investigate the seismic signatures within sedimentary basins and the crust corresponding to underlying lithospheric and asthenospheric processes. Complementary seismic data sets, including ambient-noise-derived Empirical Green’s Functions, and regional and teleseismic data recorded by EarthScope Transportable Array, will be assimilated with different full waveform inversion techniques. This project will provide the first joint inversion of all these data sets under the full waveform inversion framework for more quantitative model comparison, assessment, and interpretation of continental evolution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.