Collaborative Research: Multiscale Travel Time Tomography of the Mantle to 1000 km Depth Beneath the Western USA

在美国西部记录的遥测数据提供了有关北美地幔结构性质的信息，北美地幔是地球内部的一个体积，它是由海洋岩石圈俯冲的复杂历史形成的。 断层摄影成像的高速结构，通常归因于俯冲板，但这是不简单的，因为我们目前的理解，俯冲的地质历史的预期。 因此，这些图像包含了关于实际俯冲历史的关键信息，年轻俯冲板片的命运，以及上地幔和穿过过渡区到下地幔的对流。 受拉腊米火山影响的地区现在正在美国西部大部分地区下方经历小规模的对流，一个假定的黄石羽流（很可能）与俯冲板和小规模的下降流相互作用。 要了解地质过程的丰富性，并将各个结构相互区分开来，需要仔细而准确的地震成像。 该项目的目标是通过创建一个从地壳底部延伸到~1000 km深度的综合三维P波速度模型来测试有关美国西部复杂历史的特定假设。 地震建模将把所有可用的本地、区域和全球旅行时间数据集与地壳和过渡带结构的新约束结合起来。 此外，它使用有限频率技术（在有用的地方）和3-D波传播技术。 这项工作支持两名研究生。

Teleseismic data recorded across the western U.S. provide information on the structural nature of the mantle beneath North America, a volume of Earth's interior that has been shaped by a complex history of subduction of oceanic lithosphere. Tomography images high-velocity structures that are commonly attributed to subducted slabs but which are not as simple as expected from our current understanding of the geologic history of subduction. Hence, such images hold key information on the actual subduction history, the fate of young subducted slabs, and convective flow in the upper mantle and across the transition zone to the lower mantle. The area affected by the Laramide orogeny is now experiencing small-scale convection beneath most of the western U.S., and a presumed Yellowstone plume is (probably) interacting with subducted slab and small-scale downwellings. Understanding this richness of geological processes and resolving the individual structures from one another requires careful and accurate seismic imaging. The goal of this project is to test specific hypotheses about the complex history of the western U.S. by creating a comprehensive 3-D P-wave velocity model extending from the base of the crust to ~1000 km depth. The seismic modeling will combine all available local, regional, and global travel-time datasets with newly available constraints on crust and transition zone structure. In addition, it uses finite frequency techniques (where useful) and 3-D wave propagation techniques. This work supports two graduate students.