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且价格过高。这极大地限制了我们识别水下地震事件的来源机制的能力，以及我们对海洋下地球内部结构和过程的理解。然而，海洋岩石圈推动了许多板块构造，海洋地壳储存和回收了碳和许多有价值的资源，所以了解我们星球上这些巨大的区域是很重要的。2018年，英国国家物理实验室和国际同事证明，当应用超精密干涉激光技术对现有的电信光纤电缆（用于互联网流量）进行询问时，可以将其用作地震波探测器。这项革命性的技术为一种令人兴奋的新可能性铺平了道路：基于已经位于大多数海洋底部的电信电缆基础设施，实现全球水下地震监测网络。这项研究将集中于模拟和分析世界上首次在陆地和海底电缆上进行的地震数据实验。与地震仪在某一点记录地球运动不同，这些电缆记录的是沿着电缆在各种可控距离上的平均运动。这为创新思维带来了令人兴奋的建模挑战和机遇。研究questions1。海底电信电缆记录地震图的精度是多少？这些记录与常规地震仪的记录有何不同？这些记录为地震探测和地球成像开辟了什么样的新领域？我们能在地下看到什么以前看不到的东西？——探索!该项目将侧重于数值模拟和现场实验数据的分析。研究将集中在地震探测和利用地震波对地球成像，但将根据学生的兴趣扩展到监测环境噪声、微地震和监测海洋和固体地球的长期过程。为了解决研究问题，将承担一系列任务：1。学生将研究和模拟地震波与光纤电缆相互作用产生的信号。学生将能够通过与在陆地和水下的光纤电缆现场获得的实际数据进行比较来验证模型。2. 学生将有机会参与这些实地实验，并将了解现代激光，光学物理和光传感器的发展。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中模拟预期的基于光纤的跨海洋距离探测机制，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描述地震的特征和绘制地球内部的图像。培训将提供一项全面的培训方案，包括专门的科学培训和一般的可转移技能和专业技能。这将包括演讲和编程技巧、科学写作、网络和专业实习。您将接受地震学领域相关学科的培训，以及所需的建模、分析和成像方法，这些方法是利用地震数据对地球内部进行有效调查所必需的。

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.