RII Track 4: Illuminating the Dark Subsurface using Fiber Optic Distributed Acoustic Sensing (DAS) Array

地震学家使用地震网络记录地面振动(例如，地震/爆炸监测)并探测黑暗的地下，就像医院中的计算机断层扫描(CT)一样。一种名为分布式声学传感(DAS)的新兴技术可以将现有的电信光缆转换为每隔几米就有数千个密集分布的地震传感器。这个距离比传统地震台网几十公里的距离要密集得多，这在科学上提供了前所未有的机会。该奖项将支持共同定位的DAS/地震阵列的数据收集，以解决重要的研究问题，例如1)极小地震的破裂过程和工业运营中诱发地震的特征；2)为什么地动会在不同的区块之间发生重大变化，以及浅层土壤结构如何变化；3)地表对极端天气事件和交通及其他环境变化的响应。该奖项将支持俄克拉荷马大学的一名女性PI和一名研究生，以及两名职业生涯早期调查人员之间的合作。该项目将把PI的研究转化为DAS阵列，这可能是下一代地震阵列，并解决与俄克拉荷马州环境危害密切相关的科学问题。该项目将支持与其他州机构的合作，并改善俄克拉荷马州的整体研究基础设施。地震学家使用地震网络记录地面振动(例如，地震/爆炸监测)，并探测黑暗的地下(例如，地下成像)。近年来，地震台阵已被应用于极端天气事件、地下水变化等环境研究。由于复杂的单个地震仪的成本，扩大地震网络是具有挑战性的。一种名为分布式声学传感(DAS)的新兴技术可以将现有的电信光缆转变为密集分布的地震传感器。它的工作原理是将激光脉冲发送到光纤中，记录每隔几米由固有缺陷散射回的回波的询问(充当可跟踪的路点)，并推断由于地面振动而产生的应变变化。用于电信目的的光纤网络一直在迅速扩展，包括俄克拉荷马州地震覆盖稀少但地震活动率高的地区。利用现有基础设施，DAS阵列可以显著扩展地震监测能力，并在科学领域开启前所未有的机遇。这项RII Track-4 EPSCoR研究人员奖将支持俄克拉荷马州北部共址DAS/地震阵列的数据收集。来自加利福尼亚州的数据集将被包括在内，作为比较。这些数据集将使用高性能计算技术进行处理，以充分发挥光纤网络的潜力，并将解决重要的研究问题，包括：(1)地震地震学：DAS如何提高小震探测的分辨率和震源特征(例如，应力降和复杂性)？其性能与地震仪相比如何？(2)结构响应：DAS和节点阵列的场地响应和波形行为是否一致，它们与地下结构的性质有何关系？(3)环境地震学：DAS阵列上的天气事件有什么表现？收集的数据和研究产品将进一步加强PI在地震地震学方面的研究，并将她的研究转化为俄克拉荷马州环境问题的下一代地震阵列。该项目将支持与其他州机构的合作，并改善俄克拉荷马州的研究基础设施。研究数据集将被整合到课堂活动中，学生将体验下一代地震网络的实践经验。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。

Seismologists use seismic networks to record ground vibrations (e.g., earthquakes/explosion monitoring) and probe the dark subsurface, just as computerized tomography (CT) scans in hospitals. An emerging technology, Distributed Acoustic Sensing (DAS), can convert pre-existing telecommunication fiber cables into thousands of densely spaced seismic sensors for every few meters. This spacing is significantly denser than the tens of kilometers spacing from traditional seismic networks, providing unprecedented opportunities in science. This award will support data collection of co-located DAS/seismic array to address important research questions, such as 1) what is the rupture process of very small earthquakes and characteristics of induced earthquakes from industry operations; 2) why ground motion can change significantly from block to block, and how shallow soil structure changes; 3) how the ground surface responds to extreme weather events and traffic and other environmental changes. This award will support a female PI and a graduate student from the University of Oklahoma, and collaborations between two early-career investigators. This project will transform the PI's research into a DAS array, which is potentially the next generation of seismic array, and address scientific questions closely related to environmental hazards in Oklahoma. The project will support collaborations with other state agencies and improve overall research infrastructure in Oklahoma. Seismologists use seismic networks to record ground vibrations (e.g., earthquakes/explosion monitoring) and probe the dark subsurface (e.g., subsurface imaging). In recent years, seismic array have been applied to environmental studies, such as extreme weather events, groundwater changes. Owing to the cost of complex individual seismometers, expansion of the seismic network is challenging. An emerging technology, Distributed Acoustic Sensing (DAS), can convert pre-existing telecommunication fiber cables into densely spaced seismic sensors. It works by sending a laser pulse into the fiber, recording the interrogation with an echo scattered back by intrinsic defects every few meters (acting as trackable waypoints), and inferring strain changes due to ground vibration. Fiber networks have been rapidly expanding for telecommunication purposes, including areas that have sparse seismic coverage but a high seismicity rate in Oklahoma. Leveraging existing infrastructure, DAS array can significantly expand seismic monitoring capabilities and open unprecedented opportunities in science. This RII Track-4 EPSCoR Research Fellows award will support data collection of co-located DAS/seismic array in northern Oklahoma. Datasets from California will be included as a comparison. These datasets will be processed with high-performance computing techniques to exploit the full potential of fiber network, and will address important research questions, including: (1) Earthquake seismology: How can DAS improve resolution small earthquake detection and source characteristics (e.g., stress drops and complexity)? How does the performance compare to seismometers? (2) Structural response: Are site responses and waveform behaviors from DAS and nodal array consistent, and how are they related to properties of subsurface structure? (3) Environmental seismology: What are the manifestations of weather events on DAS array? The data collected and research products will further strengthen the PI’s research in earthquake seismology and transform her research into the next generation of seismic array to environmental problems in Oklahoma. The project will support collaborations with other state agencies and improve the research infrastructures in Oklahoma. The research dataset will be integrated into classroom activities, and students will have hands-on experiences with a next-generation seismic network.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.