EAGER: Lowering the detection threshold of Antarctic seismicity to reveal undiscovered intraplate deformation

EAGER：降低南极地震活动的检测阈值以揭示未被发现的板内变形

• 批准号: 2023355
• 负责人: Brandon Schmandt
• 金额: $ 24.6万
• 依托单位: University of New Mexico
• 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: 2020-07-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023355&HistoricalAwards=false
• 关键词: EAGER; Lowering; detection; threshold; Antarctic

Part 1: Nontechnical Unlike other locations on the globe Antarctica is not known for having large earthquakes and the remote nature and harsh conditions make it difficult to install and maintain seismometers for earthquake detection. Some researchers believe the lack of large earthquakes is due to the continent being surrounded by inactive tectonic margins. However, in the last two decades, scientists have discovered that more earthquakes occur in the interior of the continent than previously observed. This suggests that there are many earthquakes missing from historic earthquake catalogs. This study aims to find the missing earthquakes using novel earthquake detection and location techniques from seismic data collected from temporary and permanent seismic stations in Antarctica over the last 25 years. Locating these earthquakes will help understand if and where earthquakes are located in Antarctica and will help in planning future seismic deployments. As part of the project broader impacts, a field expedition with the Girls on Rock program will be conducted to teach high school age girls, and especially those from underrepresented backgrounds, data visualization techniques using scientific data. Part 2: Technical The spatial distribution of seismicity and the number of moderate magnitude earthquakes in Antarctica is not well-defined. The current catalog of earthquakes may be biased by uneven and sparse seismograph distribution on the continent. We will mine existing broadband seismic data from both permanent and temporary deployments to lower the earthquake detection threshold across Interior Antarctica, with a focus on tectonic earthquakes. The hypothesis is that Interior Antarctica has abundant moderate magnitude earthquakes, previously undetected. These earthquakes are likely collocated with major tectonic features such as the Transantarctic Mountains, the suspected Vostok collision zone, the West Antarctic Rift System, the crustal compositional boundary between East and West Antarctica, and the Cretaceous East Antarctic Rift. Previous seismic deployments have recorded earthquakes in the Antarctic interior, suggesting there are many earthquakes missing from the current catalog. We propose to use novel earthquake location techniques designed for automated detection and location using 25 years of continuous data archived at IRIS from PASSCAL experiments and permanent stations. The approach will use STA/LTA detectors on the first arrival P-wave to 90 degrees distance, Reverse Time Imaging to locate events, and beamforming at dense arrays strategically located on cratons for enhanced detection and location. The combination of detection and location techniques used in this work has not been used on teleseismic body waves, although similar methods have worked well for surface wave studies. If successful the project would provide an excellent training dataset for future scrutiny of newly discovered Antarctic seismicity with machine learning approaches and/or new targeted data collection. We plan to collaborate with Girls on Rock, a local and international organization committed to building a culturally diverse community in science, art, and wilderness exploration, in a summer field expedition and integrating computer coding into post-field scientific projects.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.

第 1 部分：非技术性 与地球上其他地方不同，南极洲并不以发生大地震而闻名，而且地处偏远且条件恶劣，因此很难安装和维护用于地震探测的地震仪。 一些研究人员认为，缺乏大地震是因为该大陆被不活跃的构造边缘包围。然而，在过去的二十年里，科学家发现非洲大陆内部发生的地震比之前观测到的要多。这表明历史地震目录中遗漏了许多地震。 本研究旨在利用过去 25 年从南极洲临时和永久地震台收集的地震数据，利用新颖的地震检测和定位技术来查找缺失的地震。定位这些地震将有助于了解南极洲是否发生地震以及发生在何处，并将有助于规划未来的地震部署。作为该项目更广泛影响的一部分，将与“摇滚女孩”计划一起进行实地考察，向高中年龄的女孩，特别是来自弱势背景的女孩，教授使用科学数据的数据可视化技术。 第 2 部分：技术 南极洲地震活动的空间分布和中度地震的数量尚不明确。由于大陆上地震仪分布不均匀且稀疏，当前的地震目录可能存在偏差。我们将从永久和临时部署中挖掘现有的宽带地震数据，以降低整个南极洲内陆地区的地震检测阈值，重点关注构造地震。假设南极洲内陆地区发生了大量此前未被发现的中级地震。这些地震可能与主要构造特征同时发生，例如横贯南极山脉、疑似东方碰撞带、西南极裂谷系统、东南极洲和西南极洲之间的地壳成分边界以及白垩纪东南极裂谷。之前的地震部署记录了南极内陆的地震，这表明当前的目录中遗漏了许多地震。我们建议使用新颖的地震定位技术，利用 PASSCAL 实验和永久台站在 IRIS 存档的 25 年连续数据进行自动检测和定位。该方法将在第一个到达的 P 波上使用 STA/LTA ​​探测器，距离为 90 度，使用逆时成像来定位事件，并在战略性位于克拉通的密集阵列上使用波束成形，以增强探测和定位。这项工作中使用的检测和定位技术的组合尚未用于远震体波，尽管类似的方法在表面波研究中效果很好。如果成功，该项目将为未来通过机器学习方法和/或新的目标数据收集对新发现的南极地震活动进行审查提供出色的训练数据集。我们计划与 Girls on Rock 合作，该组织是一个本地和国际组织，致力于在科学、艺术和荒野探索领域建立一个文化多元化的社区，进行夏季实地考察，并将计算机编码整合到实地后的科学项目中。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。