Linking Mantle Structure and Dynamics to the Landscape Evolution of the Cascadia Forearc

该项目旨在了解俯冲带（构造板块下沉到地球的地方）附近的造山过程如何受到地球表面以下数百公里处地幔物理状态的影响。本研究的重点是美国西部的卡斯卡迪亚俯冲带，在那里观察到景观地形的变化和地球深处的异常区域。为了更好地了解深层结构，来自遥远地震的能量将被用来创建3D图像。该项目的目标是通过将多种数据类型合并到单个耦合模型中来细化这些图像。为了了解造山过程，将进行模拟，预测地形如何随时间变化。结合这些方法，我们可以测试地球深处对覆盖景观演变的影响。本项目将通过联合反演合成地震数据集，并对卡斯卡迪亚南部景观演化进行数值模拟，研究地幔对卡斯卡迪亚俯冲带地表过程的影响。这个项目将有三个主要组成部分。首先，通过联合反演远震P和S数据，通过研究Vp/Vs比率并测试对不同数据子集和反演参数的敏感性，将约束整个Cascadia的板下地幔的物理性质。接下来，通过使用三维各向异性起始速度模型测试和反演数据，我们对地幔流动的理解将与各向同性速度结构相结合，以更好地约束流动的三维性质以及它与推断的底板物理状态的关系。最后，使用数值景观演化模型，该项目将重点关注南卡斯卡迪亚，以更好地约束由于底板浮力或门多西诺三重连接点迁移而引起的隆升的时间和相对重要性。该奖项反映了美国国家科学基金会的法定使命，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。

This project aims to understand how mountain building processes near subduction zones (where tectonic plates descend into the earth) may be influenced by the physical state of the mantle hundreds of kilometers beneath the earth's surface. The focus of this study is on the Cascadia subduction zone, off the western United States, where variations in the landscape topography and anomalous regions deep in the earth have been observed. To better understand the deep structure, energy from distant earthquakes will be used to create 3D images. A goal of this project is to refine these images by incorporating multiple data types into a single coupled model. To understand the mountain building process, simulations will be run which predict how topography changes through time. Combining these methods, we can test what influence the deep earth has on how the overlaying landscape evolves.This project will investigate the mantle's influence on surface processes in the Cascadia subduction zone by synthesizing seismic data sets through joint inversions and performing numerical modeling of landscape evolution for southern Cascadia. This project will have three primary components. First, by jointly inverting teleseismic P and S data, physical properties of the subslab mantle will be constrained throughout Cascadia by investigating Vp/Vs ratios and testing the sensitivity to different data subsets and inversion parameters. Next, by testing and inverting data using three-dimensional anisotropic starting velocity models, our understanding of mantle flow will be merged with isotropic velocity structure to better constrain the 3D nature of flow and how it relates to the inferred physical state of the subslab. Finally, using a numerical landscape evolution model, this project will focus in on southern Cascadia to better constrain the timing and relative importance of uplift due to either subslab buoyancy or the migration of the Mendocino triple junction.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.