Electromagnetic Array Research over a Tectonic Hotspot (EARTH)

构造热点（地球）上的电磁阵列研究

• 批准号: NE/X017591/1
• 负责人: FIONA SIMPSON
• 金额: $ 112.76万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX017591%2F1
• 关键词: Electromagnetic; Array; Research; over; Tectonic

In 2010, Iceland's volcanism claimed worldwide attention when international flights were cancelled due to ash clouds spewing from the erupting Eyjafjallajökull volcano, leaving thousands of passengers stranded. The source of Iceland's volcanism is highly controversial. Iceland is intersected by the mid-Atlantic Ridge where tectonic plates are rifting apart. However, upwelling of magma due to rifting cannot explain the region's elevation or the amount and geochemical compositions of melts, leading to the hypothesis that a mantle plume of hot material with a deep source underlies the Iceland hotspot. However, the nature, spatial extent, depth of genesis - core-mantle boundary (CMB) versus mid-mantle transition zones (410-660 km depth) - indeed, very existence of the Iceland plume are issues that are highly debated. Recent seismological models suggest that a mantle plume may rise from below Greenland, be deflected by topography at the underside of the North American tectonic plate towards Iceland and extend below the plate as far as the British Isles.With hundreds of millions of people's lives globally impacted by volcanic activity, it is essential to understand what drives eruptions by mapping magma below Earth's surface to allow mitigation strategies to be devised. 3D models of electrical conductivities and seismic velocities provide complementary information for imaging volcanic magmas because electrical conductivities and seismic velocities are affected differently by melt quantity, distribution, composition and temperature. Magnetotellurics (MT) is a geophysical technique that uses natural electric and magnetic fields induced in the Earth by interactions between the solar wind (a stream of high-energy charged particles from the Sun) and Earth's magnetosphere (a protective shield around the Earth maintained by Earth's magnetic field) to characterize Earth's electrical conductivity structure. I propose MT array measurements in Scotland, Iceland and Greenland to complement existing seismological data. The 3D electrical conductivity models of Earth's mantle and joint inversions of electromagnetic, seismological and physicochemical data that I produce will unequivocally solve controversies relating to the nature of the Iceland hotspot that cannot be addressed using a single geophysical method.It is imperative that modern societies balance their greed for energy with measures to mitigate against further anthropogenic production of greenhouse gases that drive climate change. In the UK, this realization is leading to the development of offshore wind power and proposals to bring geothermally generated, low carbon electricity from Iceland to the UK mainland via a high-voltage (HV) cable called the Atlantic Superconnection. However, development of offshore renewable energy will expose our HV power transmission network to greater risk from space-weather induced power blackouts, because hazardous geomagnetically induced currents (GICs) that flow in transmission lines during magnetic storms increase in proportion to transmission-line lengths, which can be expected to increase significantly. Space weather is listed on the National Risk Register as a medium-to-high likelihood event associated with medium-impact socioeconomic risk and the UK government recognizes the need for improved capability to forecast extreme space weather events and their impacts on ground-based technological infrastructure to enable mitigation strategies to be devised. The scaling between storm-time magnetic fields and the GICs they induce and, therefore, the vulnerability of different geographic regions to magnetic storms is determined by Earth's deep, 3D electrical conductivity structure. As well as providing constraints on the Iceland plume, my MT products will include estimates of storm-time electric fields, worst-case-scenario space weather hazard maps and probabilistic forecasts, with a particular focus on the HV subsea cable from Iceland to the UK.

2010年，冰岛的火山活动引起了全世界的关注，当时国际航班因埃亚菲亚德拉火山喷发的火山灰云而取消，导致数千名乘客滞留。冰岛火山活动的来源是非常有争议的。冰岛被大西洋中脊包围，那里的构造板块正在断裂。然而，由于裂谷的岩浆上涌不能解释该地区的海拔或熔融物的数量和地球化学成分，导致了一个假设，即地幔柱的热材料与深源下的冰岛热点。然而，性质，空间范围，深度的成因-核幔边界（CMB）与中地幔过渡区（410-660公里深）-事实上，冰岛羽的存在是高度争论的问题。最近的地震学模型表明，地幔柱可能从格陵兰岛下方升起，受到北美构造板块下方地形的影响，转向冰岛，并在板块下方延伸至不列颠群岛。由于全球数亿人的生活受到火山活动的影响，通过绘制地球表面以下的岩浆图来了解火山爆发的驱动力是至关重要的，以便制定缓解策略。电导率和地震速度的三维模型为火山岩浆成像提供了补充信息，因为电导率和地震速度受熔体数量、分布、成分和温度的影响不同。大地电磁学（MT）是一种地球物理技术，它利用太阳风（来自太阳的高能带电粒子流）和地球磁层（由地球磁场维持的地球周围的保护性屏障）之间的相互作用在地球中感应出的天然电场和磁场来表征地球的电导率结构。我建议MT阵列测量在苏格兰，冰岛和格陵兰岛，以补充现有的地震数据。地幔三维电导率模型及电磁场、我提供的地震学和物理化学数据将明确地解决与冰岛热点性质有关的争议，这些争议无法用单一的地球物理方法来解决。现代社会必须平衡对能源的贪婪，同时采取措施减轻人类进一步产生的温室气体，这些温室气体会导致气候变化变化在英国，这一认识导致了海上风力发电的发展，并提议通过称为大西洋超级连接的高压（HV）电缆将地热发电的低碳电力从冰岛带到英国大陆。然而，海上可再生能源的发展将使我们的高压输电网络面临更大的空间天气引起的停电风险，因为在磁暴期间在输电线路中流动的危险地磁感应电流（GIC）与输电线路长度成比例增加，预计会显着增加。空间天气被列入国家风险登记册，作为与中等影响社会经济风险相关的中高度可能性事件，联合王国政府认识到有必要提高预测极端空间天气事件及其对地面技术基础设施影响的能力，以便能够制定减缓战略。风暴时磁场与它们引起的GIC之间的比例关系以及不同地理区域对磁暴的脆弱性取决于地球深部的3D电导率结构。除了提供对冰岛羽流的限制外，我的MT产品还将包括风暴时间电场的估计，最坏情况下的空间天气灾害地图和概率预测，特别关注从冰岛到英国的高压海底电缆。