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

第一部分：与地球上其他地方不同，南极洲不以发生大地震而闻名，偏远的性质和恶劣的条件使安装和维护用于地震探测的地震仪变得困难。一些研究人员认为，没有发生大地震是因为大陆被不活跃的构造边缘所包围。然而，在过去的二十年里，科学家们发现，非洲大陆内部发生的地震比之前观察到的更多。这表明历史上的地震目录中遗漏了许多地震。这项研究的目的是使用新的地震探测和定位技术，从过去25年来从南极洲临时和永久地震台站收集的地震数据中寻找缺失的地震。定位这些地震将有助于了解南极洲是否以及在哪里发生地震，并将有助于规划未来的地震部署。作为更广泛影响项目的一部分，将与摇滚女孩计划一起进行一次实地考察，向高中年龄的女孩，特别是来自代表人数不足的背景的女孩传授使用科学数据的数据可视化技术。第二部分：南极洲地震活动的空间分布和中等强度地震的数量没有明确的定义。目前的地震目录可能受到非洲大陆地震仪分布不均匀和稀疏的影响。我们将从永久部署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部的地震检测门槛，重点是构造地震。假设是南极洲内部有大量的中等强度地震，以前没有检测到。这些地震可能与主要构造特征并置，如横贯北极的山脉、疑似沃斯托克碰撞带、西南极裂谷系统、东南极和西南极之间的地壳成分边界以及白垩纪的东南极裂谷。之前的地震部署记录了南极内陆的地震，这表明目前的目录中缺失了许多地震。我们建议使用新的地震定位技术，设计用于自动检测和定位，使用来自PASSCAL实验和永久站点的IRIS存档25年的连续数据。该方法将在第一个到达的P波到达90度距离时使用STA/LTA探测器，反向时间成像来定位事件，并在克拉通上战略位置的密集阵列上进行波束形成，以增强探测和定位。这项工作中使用的探测和定位技术的组合还没有被用于远程地震体波，尽管类似的方法已经很好地用于面波研究。如果成功，该项目将为今后利用机器学习方法和/或新的有针对性的数据收集对新发现的南极地震活动进行审查提供一个极好的训练数据集。我们计划与Girls on Rock合作，这是一个当地和国际组织，致力于在夏季野外考察中建立一个具有文化多样性的科学、艺术和荒野探索社区，并将计算机编码整合到野外科学项目中。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.