CAREER: Seismic Anisotropy, Symmetry and Structure - Translating Laboratory Measurements into Seismic Interpretations

职业：地震各向异性、对称性和结构 - 将实验室测量结果转化为地震解释

• 批准号: 1454829
• 负责人: Sarah Brownlee
• 金额: $ 52.72万
• 依托单位: Wayne State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-01 至 2022-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1454829&HistoricalAwards=false
• 关键词: CAREER; Seismic; Anisotropy; Symmetry; Structure

The research objective of this project is to determine the factors controlling the magnitude and symmetry of lower crustal seismic anisotropy - directional dependence of seismic velocity - from cm- to km-scale. The ability to interpret seismic data based on the elastic properties of rocks is critical to understanding the composition and structure of the middle and lower continental crust, yet there remains a distinct gap in our understanding of the causes of seismic anisotropy in the crust vs. anisotropy in the mantle. These results will have a significant impact on our ability to interpret seismic observations of crustal anisotropy, and will lay the groundwork for improving seismic methods for measuring crustal anisotropy. The knowledge gained by this work has the potential to transform the way we think about crustal seismic anisotropy, and the resulting improved understanding of the middle and lower crust will ultimately lead to improved models of seismic hazard. The proposed work also includes development of an innovative, tiered peer-mentoring approach to undergraduate research that can be applied in any discipline, and will have significant broader impacts related to undergraduate education and research, as well as participation of underrepresented minority students in a STEM discipline at an urban university. The PI proposes to improve our understanding of the causes of seismic anisotropy in the crust by developing a predictive framework linking mineralogy, texture, and structure to seismic anisotropy using middle and lower crustal rocks exposed at gneiss domes in the northeastern United States. The approach combines laboratory measurements of intrinsic, or cm-scale, elastic properties using electron backscatter diffraction (EBSD) with field measurements and mapping of 0.5-10 km-scale structures in two gneiss domes. Field and laboratory measurements will be used to model and predict the observed seismic anisotropy - magnitude and symmetry -resulting from middle and lower crustal structures at wide-ranging length-scales. Coordinated with the scientific goals of this project, she proposes to develop and implement an innovative teaching approach, Team Research, to increase the number and diversity of undergraduate students participating in research at an urban university. Team Research will be built around a tiered peer-mentoring system, where equal proportions of introductory, intermediate, and advanced undergraduate students work in teams, during a semester long course, to design and implement a field research project relevant to the scientific objectives of this study. Team Research will provide quality field and research experience in a STEM field to 60 undergraduate students from an urban university (12 per year). The anticipated increase in undergraduate students participating in research, in particular related to this project, is likely to contribute to increased diversity of undergraduate geology majors that are qualified and interested in pursuing a graduate degree.

本项目的研究目标是确定控制下地壳地震各向异性的大小和对称性的因素-地震速度的方向依赖性-从厘米到公里尺度。根据岩石的弹性性质解释地震数据的能力对于了解中下部大陆地壳的组成和结构至关重要，但我们对地壳各向异性与地幔各向异性的原因的理解仍然存在明显的差距。这些结果将对我们解释地壳各向异性地震观测的能力产生重大影响，并将为改进测量地壳各向异性的地震方法奠定基础。这项工作所获得的知识有可能改变我们对地壳地震各向异性的看法，从而改善对中地壳和下地壳的理解，最终将导致改进地震危险性模型。拟议的工作还包括开发一种创新的、分层的同行指导方法，用于本科生研究，可应用于任何学科，并将对本科生教育和研究产生更广泛的影响，以及代表性不足的少数民族学生在城市大学STEM学科的参与。PI提出，通过开发一个预测框架，将矿物学、结构和结构与地震各向异性联系起来，利用美国东北部片麻岩圆顶处暴露的中地壳和下地壳岩石，来提高我们对地壳地震各向异性原因的理解。该方法结合了实验室测量的内在，或厘米级，弹性性能，使用电子背散射衍射（EBSD）与现场测量和映射的0.5-10公里规模的结构在两个片麻岩圆顶。现场和实验室测量将用于模拟和预测观测到的地震各向异性-震级和对称性-这是由于中地壳和下地壳结构在大范围长度尺度上造成的。与该项目的科学目标相协调，她建议开发和实施一种创新的教学方法，团队研究，以增加参与城市大学研究的本科生的数量和多样性。团队研究将围绕一个分层的同行指导系统，其中平等比例的入门级，中级和高级本科生在团队中工作，在一个学期的课程，设计和实施与本研究的科学目标相关的实地研究项目。团队研究将为来自城市大学的60名本科生（每年12名）提供STEM领域的优质现场和研究经验。参与研究，特别是与本项目有关的研究的本科生的预期增加，可能有助于增加本科地质专业的多样性，这些专业有资格并有兴趣攻读研究生学位。