CAREER: Developing a Multi-Parameter Seismic Model of North America

联合约束和解释多个地震参数使地球物理学家能够更好地研究地球材料的物理性质。这样的研究可以让科学家推断温度，水含量和变形的分布。该项目旨在利用最先进的全波形反演技术和USAray在过去十年中收集的高质量波形记录，为北美开发多参数地震模型。这个社区共享的多参数地震模型将包括速度、各向异性、剪切衰减和相关不确定性的三维变化。共同解释这些参数将使调查人员能够解决与深度相关的各向异性和地幔过渡带内的水分布有关的重要科学问题。这些问题的解决对于我们认识岩石圈、软流圈和地幔过渡带的物理特征具有重要意义。此外，这个职业生涯项目将支持早期职业PI和几个博士。研究生和本科生。PI将促进地球物理教育中的高性能计算，让本科生参与研究，并参加高中生的UTD STEM夏令营。达拉斯地区有大量的非洲裔、西班牙裔和亚裔美国人社区，PI将吸引这些社区的高中生参加这次夏令营计划。开发的多参数地震模型将在线共享，供公众和研究使用。该项目的成果将通过同行评审的出版物和在国家/国际会议上的演讲进行传播。该项目将联合收割机全波形反演和高质量的USAray记录，为北美构建一个全面的地震模型，这将使该团队能够解决以下科学问题。(1)三维方位各向异性结构的综合模型将使我们能够区分“冻结”岩石圈变形和现今软流圈流动。此外，联合解释径向和方位各向异性，使他们能够测试各向异性成因假说的岩石圈中部的不连续性;（2）考虑到高的水溶解度的wadsleyite和ringwoodite，地幔过渡带可能作为一个巨大的地球内部的水水库。地震波的衰减被认为是描述水体分布的一个重要指标。通过联合解释从开发的综合模型中获得的速度和衰减结果，该项目旨在回答这样一个问题：“北美下面的地幔过渡带是否高度水合？”(3)在全波形反演应用中，量化不确定性和分辨率仍然具有挑战性。该项目将开发算法，以有效地评估后验协方差和分辨率矩阵，这将被应用于量化北美开发的多参数地震模型的不确定性。PI还将通过研讨会和暑期实习促进学生和能源行业专家之间的互动。该项目将使PI能够为地震学相关研究培训研究生和本科生。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。

Jointly constraining and interpreting multiple seismic parameters enables geophysicists to better investigate physical properties of Earth materials. Such studies may allow scientists to infer distributions of temperature, water content, and deformation. This project aims to develop a multi-parameter seismic model for North America by using state-of-the-art full waveform inversion technology and high-quality waveform records collected by the USArray over the past decade. This community-shared, multi-parameter seismic model will include 3-D variations in velocities, anisotropy, shear attenuation and the associated uncertainties. Jointly interpreting these parameters will enable the investigators to address important scientific problems related to depth-dependent anisotropy and water distribution within the mantle transition zone. Solving these issues is important for our understanding of the physical characteristics of the lithosphere, asthenosphere and mantle transition zone. Furthermore, this CAREER project will support an early career PI and several Ph.D. graduate and undergraduate students. The PI will promote high-performance computation in Geophysics education, engage undergraduate students in research and participate in UTD STEM summer camps for high school students. The Dallas area has large African, Hispanic and Asian American communities, the PI will attract high school students from these communities to participate this summer camp program. The developed multi-parameter seismic model will be shared online for public and research usages. Results from this project will be disseminated via peer-reviewed publications and presentations at national/international meetings.This project will combine full waveform inversion and high-quality USArray records to construct a comprehensive seismic model for North America, which will enable the team to tackle the following scientific problems. (1) The 3-D azimuthal anisotropy structure in the developed comprehensive model will enable us to distinguish “frozen-in” lithospheric deformation and present-day asthenospheric flows. In addition, jointly interpreting radial and azimuthal anisotropy enables them to test the anisotropy cause hypothesis for the mid-lithosphere discontinuity; (2) Considering the high water solubilities of wadsleyite and ringwoodite, the mantle transition zone might act as a huge water reservoir inside the Earth. Seismic attenuation has been considered as an important proxy for delineating the distribution of water. By jointly interpreting velocity and attenuation results taken from the developed comprehensive model, this project aims to answer the question: “Is the mantle transition zone underneath North America highly hydrated?” (3) Quantifying uncertainty and resolution is still challenging in full waveform inversion applications. This project will develop algorithms to efficiently evaluate the posterior covariance and resolution matrix, which will be applied to quantify uncertainty of the developed, multi-parameter seismic model of North America. The PI will also promote interactions between students and experts from the energy industry through workshops and summer internships. This project will enable the PI to train graduate and undergraduate students for seismology related research.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.