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

基于层析成像模型的数值模拟约束北美大陆中部和东部次大陆岩石圈地幔的结构和动力学

• 批准号: 2240943
• 负责人: Claudia Adam
• 金额: $ 17.72万
• 依托单位: Kansas State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2026-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2240943&HistoricalAwards=false
• 关键词: Structure; dynamics; subcontinental; lithospheric; mantle

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.

大多数地震发生在构造板的边缘附近或沿着构造板的边缘，引起造成它们的力的力量相当充分地理解。美国中部和东部（CEU）的地震远非任何板块边界，都是一个谜。科学家无法就他们发生的原因达成共识。亚当博士和她的团队将调查地球地幔中的对流动作如何在地面以下数百英里处导致脆皮的力量，从而导致至少一些CEUS地震。她的研究利用了来自NSF资助的国家实验的USArray的数据，其中遗漏了密集的地震仪网络来一次记录地震多年。除了彻底的CEUS地震（大小，时机和位置）的“目录”外，美国阵列还提供了有关地下结构的新信息。亚当博士将使用此信息来构建详细的计算模型，并对地壳（和地震）中的地幔对流和力量进行计算。她还将培训一名研究生，并参加堪萨斯州立大学的科学教育和针对女孩的科学教育和外展计划，科学中人数不足的团体的年轻人以及更广泛的公众。通过美国阵列和其他补充网络收集的数据为美国的地壳和地幔的表面变形和地震速度结构提供了更清晰，更准确的图像。亚当博士将使用这些数据以及Convrs地球动力学模型来评估地幔动力学对美国中部和东部的压力和板内地震性的作用。初步的步骤将使用系统的方法对几个已发表的层析成像模型进行分类，以删除虚假特征。她和她的团队将用热力学和厌氧理论来解释层析成像速度数据，以推断地幔和地壳的流变学和浮力，从而使地球动力学模型输入与地球物理观察尽可能兼容。基于先前研究的冰川等静止调整（GIA）的影响也将被代表。将将模型输出（应力轴方向和地质高度）与观察结果进行比较，并且将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态是什么？ （2）它们与板内的地震性如何相关？ （3）观察到的地震性的哪一部分与浅层地壳和岩石圈结构有关，这是由于GIA造成的，以及由于更深的过程而造成的？该项目是由NSF地球物理学计划共同资助的，由NSF地球物理学计划和既定计划共同资助，既定的竞争性研究（EPSCOR）。该奖项反映了NSF的Inforthorial Worth的构建，并具有NSF的Infortial the Internitory Worth的构建，其合法宣传的价值是依据的，影响审查标准。