Anisotropic imaging of the Alaska-Aleutian subduction zone from shear wave splitting analyses

通过剪切波分裂分析对阿拉斯加-阿留申俯冲带进行各向异性成像

基本信息

批准号：
1949210
负责人：
Colton Lynner
金额：
$ 22.31万
依托单位：
University of Delaware
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1949210&HistoricalAwards=false
关键词：
Anisotropic imaging Alaska Aleutian subduction

项目摘要

The Alaska-Aleutians subduction zone is the most tectonically active convergent margin in North America and represents an area of both scientific and societal relevance. The region has hosted several large mega-thrust earthquakes, has a lot of volcanic activity, and has the potential of generating a tsunami. The region is also an ideal natural laboratory to study subduction systems due to the long-term subduction of the Pacific Plate, volcanism associated with subduction that builds the Aleutian Islands, and high earthquake activity. This project will examine the mantle processes that drive subduction using both onshore and offshore earthquake data. Mantle deformation will be examined within the different portions of the subduction system. The techniques to be used are complementary and when combined will provide a full picture of the subduction zone region. This integrated view will allow an investigation of the operation and interactions of the different subduction regions to create the Alaska-Aleutians subduction zone that is seen today. This project will bring an undergraduate student to the University of Delaware for a summer research experience internship and will provide training for a doctoral student. This project also will include collaborative outreach activities with the University of Delaware Disaster Research Center. This project is a multi-faceted examination of seismic anisotropy throughout the Alaska-Aleutians subduction zone (AASZ). Multiple datasets and techniques will be used in sequence to gain insights into the interactions of the different parts of the subduction system. Shear wave splitting analyses will be performed on a variety of seismic phases that are each tailored to best assess a portion of the AASZ: 1) local-S splitting at island arc stations that target the mantle wedge, 2) source-side splitting in geometries that isolate deformation within the downgoing slab, 3) source-side splitting that targets dynamics in the sub-slab mantle, and 4) traditional splitting at the ocean-bottom and onland stations. Each set of splitting observations targets a specific subduction zone region, with associated targeted questions, in such a way as to be easily integrated together. Combining the suite of complementary techniques will create a complete view of the deformation and active dynamics leading to the modern day AASZ. These results will refine the understanding of slab deformation in the mantle, the association of mantle wedge dynamics and along strike variations in arc magmatism, and the overall evolution of mantle flow beneath the Pacific as it morphs from a surface plate into a subducting slab.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.

阿拉斯加-阿留申群岛俯冲带是北美构造最活跃的汇聚边缘，代表着具有科学和社会意义的区域。该地区曾发生过多次大型逆冲地震，火山活动频繁，有可能引发海啸。由于太平洋板块的长期俯冲、与形成阿留申群岛的俯冲相关的火山作用以及强烈的地震活动，该地区也是研究俯冲系统的理想天然实验室。该项目将利用陆上和海上地震数据来研究驱动俯冲的地幔过程。将在俯冲系统的不同部分内检查地幔变形。所使用的技术是互补的，结合起来将提供俯冲带区域的全貌。这种综合视图将允许对不同俯冲区域的运作和相互作用进行调查，以创建今天所看到的阿拉斯加-阿留申群岛俯冲带。该项目将带一名本科生到特拉华大学进行暑期研究体验实习，并将为一名博士生提供培训。该项目还将包括与特拉华大学灾害研究中心的合作外展活动。该项目是对整个阿拉斯加-阿留申群岛俯冲带 (AASZ) 地震各向异性的多方面研究。将按顺序使用多个数据集和技术来深入了解俯冲系统不同部分的相互作用。剪切波分裂分析将在各种地震阶段进行，每个地震阶段都经过专门设计，以最好地评估 AASZ 的一部分：1）针对地幔楔的岛弧台站的局部 S 分裂，2）几何形状的源侧分裂隔离下行板片内的变形，3）针对子板片地幔动力学的源侧分裂，以及4）海底和陆上站的传统分裂。每组分裂观测都针对特定的俯冲带区域，并具有相关的目标问题，以便轻松整合在一起。结合全套互补技术将创建现代 AASZ 的变形和主动动力学的完整视图。这些结果将完善对地幔板片变形、地幔楔动力学与弧岩浆沿走向变化之间的关联，以及太平洋下方地幔流从表面板块转变为俯冲板片时的整体演化的理解。该奖项反映了 NSF 的法定使命，并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，被认为值得支持。