CAREER:Potential of fiber acoustic sensing in the next-generation seismic networks

科学家们使用大型地震传感器网络来探测地震引起的地面振动，以便了解地震的物理性质，并帮助减轻相关危害。在地震活动频繁的地区，如加利福尼亚，有密集的网络，每10到30公里有一个地震传感器。然而，过去的大地震告诉我们，这个站点密度仍然不够。由于高度复杂的浅层土壤结构，地震震动会在不同的地块之间发生巨大变化。此外，目前的地震台网无法探测到许多小地震，这使我们的断层图像模糊不清。有了更密集的地震网络，科学家将能够更好地绘制地震断层并监测它们的活动，同时也能提供更清晰的地球内部图像。分布式声传感（DAS）是一项新兴技术，它通过从光纤的一端向光纤发射激光脉冲并询问光纤缺陷散射的“回声”，将每米长的光纤转换为地震传感器。DAS提供了一种可扩展且经济实惠的方式来部署密集的地震网络。该CAREER项目将建设Pasadena阵列，这是第一个连续的城市规模光纤地震网络，以探索DAS在下一代地震网络中的潜力。该研究人员将与帕萨迪纳市合作，将该市现有的电信光纤网络改造成在10公里范围内拥有5万个传感器的地震阵列。帕萨迪纳阵列将是一个独特的平台，用于测试和表征不同一代的DAS仪器，开发数据处理算法，并探索地震学中的应用。台站密度的数量级增加将推动地震探测、盆地结构成像和灾害评估/减灾的极限。最终，帕萨迪纳阵列将作为一个模板，在南加州建立一个百万传感器的地震网络，并改变我们在全国和全球范围内设计、建造和使用地震网络的方式。该项目的更广泛影响包括提高对地震影响的认识，以及让帕萨迪纳学校系统的学生更好地了解地震危害。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Scientists use large networks of seismic sensors to detect ground vibrations caused by earthquakes, in order to understand their physics and help mitigate related hazard. In regions with high seismic activity, such as California, there are dense networks with one seismic sensor every 10 to 30 km. However, past large earthquakes taught us that this station density is still not enough. Earthquake shaking can change dramatically from block to block, due to highly complex shallow soil structures. Furthermore, many small earthquakes are not detected by the current seismic networks, smearing our images of faults. With denser seismic networks, scientists will be able to better map earthquake faults and monitor their activities, also to provide more clear pictures of Earth interior.Distributed acoustic sensing (DAS) is an emerging technology that converts every meter of a long optical fiber to a seismic sensor, by shining a laser pulse into the fiber from one end and interrogating the "echo" scattered from fiber defects. DAS provides a scalable and affordable way to deploy a dense seismic network. This CAREER project will build the Pasadena Array, the first continuous city-scale fiber seismic network, to explore the potential of DAS in the next-generation seismic networks. The researcher will collaborate with the City of Pasadena to transform an existing telecommunication fiber network owned by the city to a seismic array with 50,000 sensors within 10km. The Pasadena Array will be a unique platform to test and characterize different generations of DAS instruments, develop data processing algorithms, and explore applications in seismology. The orders of magnitude increase in station density will push the limits of earthquake detection, basin structure imaging, and hazard assessment/mitigation. Ultimately, the Pasadena Array will serve as a template to build a million-sensor seismic network in Southern California, and transform how we design, build, and use seismic networks nationally and globally.The Broader Impacts of the project include the benefits enhanced knowledge of the impacts of earthquakes and the involvement of students in the Pasadena school system in better understanding seismic hazards.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.