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

该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-从厘米尺度到公里尺度。根据岩石的弹性性质解释地震数据的能力对于理解中、下大陆地壳的组成和结构至关重要，但我们对地壳地震各向异性和地幔各向异性的原因的理解仍然存在着明显的差距。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。通过这项工作获得的知识有可能改变我们对地壳地震各向异性的看法，由此产生的对中地壳和下地壳的更好的理解最终将导致改进的地震危险模型。拟议的工作还包括开发可应用于任何学科的本科研究的创新、分级同行指导方法，并将对本科教育和研究以及城市大学代表不足的少数族裔学生参与STEM学科产生重大而广泛的影响。PI建议利用美国东北部片麻岩穹顶出露的中下层地壳岩石，开发一个将矿物学、结构和结构与地震各向异性联系起来的预测框架，以提高我们对地壳地震各向异性原因的理解。该方法将使用电子背散射衍射(EBSD)对固有的或厘米尺度的弹性性质的实验室测量与现场测量和绘制两个片麻岩穹顶中0.5-10公里尺度的结构图相结合。将使用现场和实验室测量来模拟和预测观测到的地震各向异性--震级和对称性--由大范围长度尺度上的中地壳和下地壳结构引起。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，以增加城市大学本科生参与研究的数量和多样性。团队研究将围绕分层的同行指导系统建立，在该系统中，同等比例的初级、中级和高级本科生在整个学期的课程中以小组形式工作，以设计和实施与本研究的科学目标相关的实地研究项目。团队研究将为一所城市大学的60名本科生提供STEM领域的高质量领域和研究经验(每年12名)。参与研究的本科生人数预计将增加，特别是与该项目相关的研究，这可能有助于增加符合条件并有兴趣攻读研究生学位的地质学专业本科生的多样性。

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.