Earthquakes and Imaging beneath the Oceans using Submarine Telecoms Cables as Seismometers

今天，虽然地球表面的70%是水，但几乎所有的地震传感器都在陆地上，因为在海底安装电缆传感器太困难，而且价格昂贵。这大大限制了我们确定水下地震事件的震源机制的能力，以及我们对海洋之下地球内部结构和过程的理解。然而，海洋岩石圈驱动了许多板块构造，海洋地壳储存和储存了碳和许多有价值的资源，因此了解我们星球上这些巨大的区域非常重要。2018年，英国国家物理实验室和国际同事，表明现有的电信光纤电缆（用于互联网通信）可以用作地震波探测器，当超精密干涉激光技术应用于询问它们时。这项革命性的技术为一个令人兴奋的新可能性铺平了道路：基于大多数海洋底部的电信电缆基础设施，实施全球水下地震监测网络。这项研究将侧重于对世界上第一个陆地和海底电缆实验所获得的地震数据进行建模和新颖分析。与记录某一点的地球运动的地震仪不同，这些电缆记录的是沿电缆沿着不同可控距离的平均运动。这为创新思维带来了令人兴奋的建模挑战和机遇。研究问题1.地震图记录在海底电信电缆上的准确性如何？2.这些记录与常规地震仪的记录有何不同？3.这些记录为地震探测和地球成像打开了什么新的利基市场？4.在地下我们能看到什么我们以前看不到的东西？- 探索！方法本项目将侧重于数值模拟和现场实验数据的分析。该研究将侧重于地震探测，以及利用地震波对地球进行成像，但将根据学生的兴趣扩展到监测环境噪声，微震以及监测海洋和固体地球中的长期过程。为了解决研究问题，将进行一系列的任务：1。学生将研究和模拟地震波和光纤电缆之间相互作用产生的信号。学生将能够通过与陆地和水下光纤电缆现场采集的实际数据进行比较来验证模型。2.学生将有机会参加这些实地实验，并将了解现代激光，光学物理和光学传感器的发展。3.从一组陆地和海底电缆的实验数据开始，学生将在浅水和深水沃茨中模拟预期的基于光纤的探测机制，评估基于海底电缆的全球地震网络的可行性。4.从地震中获得的数据将用于地震的定位和地球内部的成像。培训将提供一个全面的培训方案，包括专业科学培训和通用的可转让的专业技能。这将包括演示和编程技能，科学写作，网络和专业安置。您将接受地震学领域相关学科的培训，沿着使用地震数据有效询问地球内部所需的建模，分析和成像方法。

Today, whilst 70% of the Earth's surface is water, almost all seismic sensors are on land because it is too difficult and prohibitively expensive to install cabled sensors on the sea floor. This substantially limits our ability to identify the source mechanisms of underwater seismic events and our understanding of the internal structure and processes in the Earth beneath oceans. Yet oceanic lithosphere drives much plate tectonics, and oceanic crust stores and recycles carbon and many valuable resources, so understanding these huge areas of our planet is important.In 2018, the UK National Physical Laboratory and international colleagues, demonstrated that existing telecommunication optical fibre cables (used for Internet traffic) can be used as seismic (earthquake) wave detectors when ultra-precise interferometric laser techniques are applied to interrogate them. This revolutionary technique paves the way to an exciting new possibility: the implementation of a global monitoring network for underwater earthquakes based on the telecommunications cable infrastructure that already lies on the bottom of most seas and oceans. This research will focus on modelling and novel analysis of seismic data acquired with world-first experiments on terrestrial and submarine cables. In contrast with seismometers which record earth motion at a point, these cables record motion averaged over various controllable distances along the cable. This poses exciting modelling challenges and opportunities for innovative thinking. Research questions1. With what accuracy can seismograms be recorded on submarine telecoms cables?2. How do these recordings differ from recordings made on regular seismometers?3. What novel niche do the recordings open for earthquake detection and imaging of the Earth?4. What can we see in the subsurface that we could not see previously? - Explore!MethodologyThis project will focus upon numerical modelling and analysis of experimental data from field experiments. The research will focus on earthquake detection, and the use of seismic waves for imaging the Earth, but will extend to the monitoring of environmental noise, microseisms and the monitoring of longer terms processes in the oceans and solid Earth, depending on the interests of the student. To address the research questions a series of tasks will be undertaken:1. The student will study and model the signals resulting from the interaction between seismic waves and optical fibre cables. The student will be able to validate the model by comparison with actual data acquired in the field with optical fibre cables on land and underwater. 2. The student will have the opportunity to participate in these field experiments, and will learn about modern lasers, optical physics and the development of optical sensors. 3. Starting from experimental data from a set of terrestrial and submarine cables, the student will model the expected fibre-based detection mechanism across oceanic distances, in both shallow and deep waters, assessing the feasibility of a global seismic network based on submarine cables. 4. Data acquired from earthquakes will be used to characterise the earthquakes and to image the Earth's interior. TrainingA comprehensive training programme will be provided comprising both specialist scientific training and generic transferable and professional skills. This will include presentation and programming skills, scientific writing, networking, and a professional placement. You will be trained in the relevant disciplines which underlie the field of seismology, along with the required modelling, analysis and imaging methods necessary to use the seismic data for effective interrogation of the Earth's interior.