CAREER: Along-Strike Variation: A Comparative Study of Subduction Zones at Multiple Scales Using Joint Receiver Function and Tomographic Inversion

俯冲带是两个构造板块汇聚的地方，其中一个板块在另一个板块之下。 俯冲带在驱动板块构造和主办大地震，火山爆发，海啸和山体滑坡方面发挥着重要作用，其中许多对自然系统和社会产生重大影响。最近的一项研究表明，大多数俯冲带可以在250年的时间间隔内产生震级等于或大于8.5的地震。俯冲地震的位置和震级受多种因素的强烈影响，这些因素在单个俯冲带内和全球俯冲系统之间存在显著差异。然而，广泛观察到的变化之间的原因，影响和关系还没有得到很好的理解。CAREER项目的目标是利用先进的地震模拟方法，对五个代表性俯冲带的特征有一个新的认识。大量的地球物理数据集现在为我们提供了一个很好的机会来构建俯冲系统的比较模型。通过创建高质量的俯冲系统模型，该项目将为理解基本俯冲过程提供新的见解。该项目将涉及不同职业早期阶段的青年科学家的发展，包括一名职业早期的女地球科学家、本科生和研究生。更广泛地说，该项目旨在为本科生开发教学工具，为K-12教育提供机会，并提高公众对俯冲研究重要性的认识。三个基本问题是在这项研究的核心：什么是规模的沿走向变化（分段）的俯冲性质，以及在何种程度上是他们相关的从一个俯冲带到另一个？不同尺度的地幔流如何相互作用并控制沿走向的变化，例如，熔体生产力和岩浆作用？下行板块和上覆板块的性质如何影响上地幔沿走向的变化？为了充分理解分段，多个俯冲带的高分辨率层析成像模型是非常必要的，以便比较分段的特征和尺度。该项目将使用联合接收器功能（RF）和全波层析成像（FWT）调查五个俯冲环境的结构。RF将识别和描绘尖锐的速度不连续性。先进的FWT将为地壳和上地幔结构成像提供强有力的手段。RF和FWT的组合将检测各种地震特征。本项目的成果将有助于回答以下两个方面的问题：1）对俯冲系统沿走向变化的类型和规模有新的认识。从地壳到上地幔的什么结构相关性可以被成像，从而可以洞察沿走向的变化？细分的维度是什么？俯冲参数与沿走向变化的关系是什么？分段作用对地表构造岩浆作用有何影响？2)多尺度地幔流及其对沿走向变化影响的关键认识。哪些地震特征与大规模俯冲驱动过程有关？区域地质和构造过程的作用是什么？板块驱动流和区域对流之间的相互作用如何与分割有关？小尺度对流是否控制分段特征的间距？研究部分将辅之以教育和外联工作，重点是为五所学院的本科生举办夏季地震学教育讲习班。PI还将通过女孩公司向服务不足的8 - 12年级女孩介绍地球科学。尤里卡！程序.此外，PI将建立一个机制，利用所采用的移动式阵列地震站进行公众宣传。通过综合工作，PI旨在致力于研究，教学和外展活动，将积极影响俯冲社区和公众。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Subduction zones are where two tectonic plates converge, and one plate is thrusting beneath the other. Subduction zones play a major role in driving plate tectonics and host great earthquakes, volcanic eruptions, tsunamis, and landslides, many of which have significant impacts on natural systems and society. A recent study showed that most subduction zones can generate earthquakes with magnitude equal to or greater than 8.5 over a 250-year interval. The location and magnitude of subduction earthquakes are strongly influenced by many factors, which vary significantly within a single subduction zone and among global subduction systems. However, the causes, effects, and relationships among the widely observed variations are not well understood. The objective of the CAREER project is to develop a new understanding of the characteristics at five representative subduction zones with advanced methods of seismic modeling. A large collection of geophysical datasets now provides us with an excellent opportunity to construct comparative models of the subduction system. By creating high-quality models of subduction systems, the project will provide new insights into understanding of fundamental subduction processes. This project will involve the development of young scientists at different early career stages, including an early-career female geoscientist, undergraduate and graduate students. More broadly, this project aims to develop teaching tools for undergraduate students, to provide opportunities for K-12 education, and to increase public knowledge of the importance of subduction research. Three fundamental questions are at the core of this research: What are the scales of along-strike variations (segmentation) of subduction properties and to what degree are they correlated from one subduction zone to another? How do various scales of mantle flow interact with each other and control along-strike variation in, e.g., melt productivity and magmatism? And how do properties of the downgoing and overriding plates contribute to along-strike variation within the upper mantle? To fully understand segmentation, high-resolution tomographic models of multiple subduction zones are critically necessary in order to compare the characteristics and scales of segmentation. This project will investigate the structure of five subduction environments, using a joint receiver function (RF) and full-wave tomography (FWT). RFs will identify and delineate sharp velocity discontinuities. An advanced FWT will provide a powerful way to image the structure of the crust and upper mantle. Combination of RFs and FWT will detect a variety of seismic features. The outcomes of this project will help answer questions in the two following areas: 1) A new understanding of the types and scales of along-strike variations in subduction system. What structural correlations from crust to upper mantle can be imaged that may give insight to along-strike variations? What are the dimensions of segmentation? What are the relationships of subduction parameters with along-strike variations? What are the influences of segmentation on surface tectonomagmatism? 2) A key understanding of multi-scale mantle flow and the influences on along-strike variations. What seismic features are related to large-scale subduction-driven processes? What are the roles of regional geology and tectonic processes? How do interactions between plate-driven flow and regional convection relate to segmentation? Does small-scale convection control the spacing of segmented features? The research component will be complemented by an education and outreach effort, which will focus on developing a summer seismology education workshop for the Five-College undergraduate students. The PI will also introduce Earth science to underserved 8th-12th grade girls through the Girls Inc. Eureka! Program. Furthermore, the PI will establish a mechanism for public outreach using the adopted Transportable Array seismic station. Through the integrated work, the PI aims to devote to research, teaching, and outreach activities that will positively impact the subduction community and general public.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.