EAR-PF: Investigating the lithospheric structure and the origins of seismic anomalies in the Southwestern United States using a joint seismic analysis

Eva Golos博士被授予EAR博士后奖学金，在Karen Fischer教授的指导下在布朗大学开展研究和教育计划。她的目标是通过整合来自不同类型地震波的信息来了解美国西南部岩石圈的结构和演化。这项研究将集中于各种因素，如温度、岩石成分和熔融如何控制当今岩石圈的结构和强度，以及这种相互作用如何引导地质时间尺度上的构造演化。Golos博士将利用各种地震数据开发一种新的反演方法，包括面波、穿越岩石圈的地震波，以及从一种地震波反射或转换成另一种地震波的地震波。输入数据的组合将产生分辨率更高的模型。对得到的地震模型的解释将与熔融和各向异性(地震波传播速度与振动方向的关系)的影响的正演模拟一起进行。必须综合来自多个尺度的信息，从颗粒尺度到地幔的尖锐不连续，再到岩石圈的整个深度范围。这些发现将深入了解岩石圈属性如何影响变形和地表动力学，并对地震和火山等自然灾害产生影响。这些应用程序为推广活动提供了一个自然的起点，这些活动将通过针对小学受众的项目以及通过教学和本科生指导来完成。许多悬而未决的问题与大陆岩石圈的性质有关，特别是温度、成分变化、各向异性结构以及部分熔体的存在和丰富的相对作用。这项工作旨在了解这些因素及其对岩石圈结构、厚度和强度的影响，对变形和地表对构造力的响应，以及对大陆岩石圈的演化和命运的影响。美国西南部将作为案例研究，探索与科罗拉多高原、盆地和山脉省以及里奥格兰德裂谷相关的地球物理异常的起源。采取的方法将是双管齐下的。首先，将开发一个包含各种网络的地震模型，其中包括USArray可移动阵列、地球镜灵活阵列部署和永久宽带站。通过对大量地震数据进行贝叶斯反演，包括P-to-S和S-to-p接收函数、瑞雷波相速度频散和体波反射率自相关图，将生成剪切波速和不连续结构模型。这些数据的互补性将有助于解决平滑的大尺度特征以及尖锐的边界和不连续。接收函数在不同频段和不同方向的变化可以分别用来推断界面的锐度和各向异性。这项研究的第二部分涉及使用正演模拟来估计热、成分和与熔融有关的性质对地震结构的相对影响，并提供在区域到大陆尺度上它们相互作用的约束。该项目由地球科学部门的地球物理项目和既定的激励竞争研究计划(EPSCoR)办公室共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

An EAR Postdoctoral fellowship has been awarded to Dr. Eva Golos to carry out research and education plans at Brown University under the mentorship of Professor Karen Fischer. She aims to understand the structure and evolution of the lithosphere under the southwestern United States by integrating information from different types of seismic waves. The research will focus on how various factors such as temperature, rock composition, and melting control the structure and strength of the present-day lithosphere, and how this interplay has guided tectonic evolution over geologic time scales. Dr. Golos will develop a new inversion method using a variety of seismic data, including surface waves, seismic waves that traverse the lithosphere, and those that have been reflected or converted from one type of seismic wave to another. The combination of input data will produce models with more resolution. Interpretation of the resulting seismic model will be carried out alongside forward-modeling of the effects of melt and anisotropy (the dependence of the speed of seismic wave propagation on vibration direction). Information from a number of scales must be synthesized from the grain-scale to sharp discontinuities in the mantle to the entire depth extent of the lithosphere. The findings will yield insight into how lithospheric properties affect deformation and surface dynamics, with implications for natural hazards such as earthquakes and volcanoes. These applications provide a natural starting point for outreach activities, which will be done through programs aimed at elementary school audiences as well as through teaching and undergraduate mentoring.Many unanswered questions pertain to the nature of the continental lithosphere, and particularly the relative roles of temperature, compositional variations, anisotropic structures, and the presence and abundance of partial melt. This work aims to understand these factors and their effects on lithospheric structure, thickness, and strength; on deformation and the response at the surface to tectonic forces; and on the evolution and fate of the continental lithosphere. The southwestern United States will be used as a case study, to probe the origins of geophysical anomalies associated with the Colorado Plateau, Basin and Range Province, and Rio Grande Rift. The approach taken will be two-pronged. First, a seismic model will be developed incorporating a variety of networks including the USArray Transportable Array, Earthscope FlexArray deployments, and permanent broadband stations. A model of shear wavespeed and discontinuity structure will be generated through a Bayesian inversion of a plethora of seismic data, including P-to-s and S-to-p receiver functions, Rayleigh wave phase velocity dispersion, and body wave reflectivity autocorrelograms. The complementary nature of these data will help resolve smooth large-scale features as well as sharp boundaries and discontinuities. Variations in receiver functions at different frequency bands, and from different directions, can be used to infer the sharpness and the anisotropic properties of interfaces, respectively. The second part of this investigation involves using forward modeling to estimate the relative effects of thermal, compositional, and melt-related properties on seismic structure, and to provide constraints on their interplay at regional-to-continental scales. This project was funded jointly by the Geophysics program in the Division of Earth Sciences and the Established Program to Stimulate Competitive Research (EPSCoR) office.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.