Collaborative Research: Incoming plate and forearc structure of the Semidi and SW Kodiak Segments offshore Alaska Peninsula from 3-D active-source and local earthquake tomography

合作研究：阿拉斯加半岛近海塞米迪和西科迪亚克段的传入板块和弧前结构，来自 3D 主动源和当地地震层析成像

• 批准号: 1947758
• 负责人: Anne Becel
• 金额: $ 31万
• 依托单位: Columbia University
• 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: 2020-04-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1947758&HistoricalAwards=false
• 关键词: Collaborative; Research; Incoming; plate; forearc

The largest earthquakes and associated tsunamis as well as volcanic eruptions are found at subduction zones where one tectonic plate dives beneath another. A prominent example in North America is the subduction zone offshore of the Alaska Peninsula, where some of the largest earthquakes ever recorded in modern times have occurred, like the great earthquake of 1938 and the devastating 1964 M9.2 Prince William earthquake. In this region the history of large and small earthquakes and how strongly the two plates are locked together vary substantially and rapidly along the margin. Many questions, however, remain unanswered about the ability of the subduction zone to generate large earthquakes. This project will analyze and interpret recordings of earthquakes that were collected as part of a larger NSF-GeoPRISMS funded Alaska Amphibious Community Seismic Experiment (AACSE) in 2018-2019. The seismic data, recorded by a dense array of offshore and onshore seismometers, will allow the development of a three-dimensional image of the geological structure and physical properties of this subduction zone down to a depth of 100 km. The quality of the images will be high enough to examine structures that have been previously proposed to explain changes in the seismic behavior of the plate boundary in this area and at other subduction zones worldwide. The project supports the training of two graduate students.Three-dimensional seismic tomography studies will be conducted of P- and S-wave structure based on controlled-source and local earthquake data recorded by the AACSE amphibious array. The project will address the following key question: To what extent is the segmentation of the Alaska Peninsula margin in seismogenic properties, seismicity during the interseismic period, and plate coupling controlled by along-strike and downdip variations in upper continental plate structure, composition, and/or downgoing oceanic plate physical properties and structures such as seamounts, bending faults and fracture zones? The 3-D seismic velocity models will be used to investigate along-strike variations in water input into the subduction zone, as well as depth extent of the presumed hydrated oceanic mantle and whether or not water is delivered to seismogenic depths where it could influence megathrust seismic properties. By mapping seismic velocity anomalies along the plate interface, the plate interface relief and the presence (or lack thereof) of subducted structural anomalies such as seamounts chains, swell and fracture zones, and their presumed role in contributing to rupture segmentation and variations in the geodetically inferred plate interface locking, will be examined. An improved understanding of subduction zone processes associated with large earthquakes is important for assessing earthquakes and tsunami hazards at the Alaska Peninsula subduction zone. Although this project focuses on the Alaska Peninsula subduction zone, the scientific question applies across many subduction zones worldwide.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.

在俯冲带中发现了最大的地震和相关的海啸以及火山喷发，其中一个构造板在另一个构造板上潜水。北美一个著名的例子是阿拉斯加半岛近海的俯冲带，现代有史以来记录的一些最大的地震发生了，例如1938年的巨大地震和1964年毁灭性的1964年M9.2 M9.2威廉·威廉王子地震。在该地区，大型和小地震的历史以及两个板被锁定在一起的强烈沿边缘差异很大。但是，许多问题仍然没有关于俯冲带产生大地震的能力的答复。该项目将分析和解释地震记录，这些地震是在2018 - 2019年在阿拉斯加两栖社区地震实验（AACSE）资助的较大的NSF地球策略中收集的。地震数据由密集的海上和陆上地震仪记录，将允许发展该俯冲带的地质结构和物理性质的三维图像，以至于深度为100 km。图像的质量将足够高，可以检查以前提出的结构，以解释该区域和全球其他俯冲区域板边界的地震行为的变化。该项目支持对两名研究生的培训。将根据AACSE两栖阵列记录的受控源和局部地震数据进行三维地震层析成像研究。该项目将解决以下关键问题：在地震生成特性，地震时期内的地震性以及由上部和下降的大陆板板结构中的沿形成和下降的变化控制的板耦合在多大程度上，地震性以及板耦合，以及/或下去海洋板的物理特性和/或下去的海洋板质量和结构，例如潮汐和/或沿层层造成的毛水效果和床无然？ 3-D地震速度模型将用于研究水输入俯冲带的撞击变化，以及假定水合的海洋披风的深度，以及是否将水递送到可以影响超级震荡的地震特性的中性深度。 通过绘制沿板界面的地震速度异常绘制俯冲结构异常（例如，隔离式链，膨胀链，膨胀和破裂区域）的板界面的浮雕以及（或缺乏的）（或缺乏），以及它们在地球上的分割和变化方面的作用，将在地球上进行地理板的板块插图锁定。对与大地震相关的俯冲带过程的提高了解对于评估阿拉斯加半岛俯冲带的地震和海啸危害很重要。尽管该项目着重于阿拉斯加半岛俯冲区，但科学问题适用于全球许多俯冲区域。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的审查标准的评估来获得支持的。