Structure and dynamics of the subcontinental lithospheric mantle over the Central and Eastern North American continent, constrained by numerical modeling based on tomography models

大多数地震都发生在构造板块的边缘或沿着边缘，引起地震的力量已经被合理地理解了。美国中部和东部（CEUS）的地震远离任何板块边界，有点神秘;科学家们无法就它们发生的原因达成一致。亚当博士和她的团队将调查地表以下数百英里的地幔中的对流运动如何影响脆性地壳中的力量，从而导致至少一些CEUS地震。她的研究利用了来自USAray的数据，USAray是一个由NSF资助的国家实验，其中一个密集的地震仪网络被排除在外，一次记录地震数年。除了CEUS地震（规模，时间和位置）的全面“目录”外，US Array还提供了有关地下结构的新信息。亚当博士将利用这些信息来建立详细的计算模型，并计算地幔对流和这种对流可能引起的地壳（和地震）中的力。她还将培训一名研究生，并参加堪萨斯州立大学为女孩、来自科学领域代表性不足的群体的年轻人以及更广泛的公众举办的科学教育和外展项目。通过美国阵列和其他补充网络收集的数据提供了美国地壳和地幔表面变形和地震速度结构的更清晰和更准确的图像。亚当博士将使用这些数据，与ConvRS地球动力学模型一起，评估地幔动力学对美国中部和东部应力和板内地震活动的作用。第一步将是使用系统方法对几个已发表的断层扫描模型进行分类，以去除虚假特征。她和她的团队将用热力学和滞弹性理论解释层析速度数据，以推断地幔和地壳流变学和浮力，使地球动力学模型输入尽可能与地球物理观测兼容。冰川均衡调整（GIA）的影响，根据以前的研究，也将代表。将模型输出（应力轴方向和大地水准面高度）与观测结果进行比较，并评估这些结果对参数变化的敏感性。亚当博士计划解决的主要问题是：（1）次大陆岩石圈地幔的结构和动力学是什么？(2)它们与板内地震活动有何关联？（3）观测到的地震活动中，哪一部分与地壳和岩石圈的浅部结构有关，哪一部分是由于GIA引起的，哪一部分是由于更深的过程引起的？该项目由NSF地球物理计划和激励竞争性研究的既定计划（EPSCoR）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。

Most earthquakes happen near or along the edges of tectonic plates, and forces causing them are reasonably well understood. Earthquakes in the Central and Eastern United States (CEUS), far from any plate boundary, are a bit of a mystery; scientists cannot agree on why they happen. Dr. Adam and her team will investigate how convective motions in the Earth's mantle, hundreds of miles below the surface, may contribute to forces in the brittle crust, causing at least some CEUS earthquakes. Her study makes use of data from the USArray, an NSF-funded national experiment in which a dense network of seismometers was left out to record earthquakes for years at a time. In addition to a thorough 'catalogue' of CEUS earthquakes (size, timing and location), the US Array has provided new information on the structure of the subsurface. Dr. Adam will use this information to build detailed computational models and perform calculations of mantle convection and forces in the crust (and earthquakes) this convection might cause. She will also train a graduate student and participate in Kansas State University's science education and outreach programs for girls, young people from groups that are underrepresented in the sciences, and the broader public. Data collected through the US Array and other complementary networks have provided a much clearer and more accurate image of surface deformation and seismic velocity structure of the crust and mantle in the United States. Dr. Adam will use these data, together with ConvRS geodynamic models, to assess the role of mantle dynamics on stresses and intraplate seismicity in the Central and Eastern United States. A preliminary step will be to sort through several published tomographic models using a systematic method to remove spurious features. She and her team will interpret tomographic velocity data with thermodynamic and anelasticity theory to infer mantle and crust rheology and buoyancy forces, making geodynamic model inputs as compatible as possible with geophysical observations. The effects of the Glacial Isostatic Adjustment (GIA), based on previous studies, will also be represented. Model outputs (stress axis orientation and geoid height) will be compared to observations, and sensitivity of these results to parameter variations will be assessed. The main questions Dr. Adam plans to address are (1) What are the structure and dynamics of the sub-continental lithospheric mantle? (2) How do they correlate with intraplate seismicity? and (3) Which part of the observed seismicity is related to shallow crustal and lithospheric structures, which is due to GIA, and which is due to deeper processes?This project is jointly funded by the NSF Geophysics Program and the Established Program to Stimulate Competitive Research (EPSCoR).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.