Electromagnetic Array Research over a Tectonic Hotspot (EARTH)

2010年，由于埃亚菲亚德拉火山喷发的火山灰云喷出，国际航班被取消，导致数千名乘客滞留，冰岛的火山活动引起了全世界的关注。冰岛火山喷发的源头存在很大争议。冰岛与大西洋中部海脊相交，那里的构造板块正在裂开。然而，裂谷作用导致的岩浆上涌无法解释该地区的海拔高度或熔体的数量和地球化学成分，从而导致了冰岛热点背后有深源的地幔热流的假设。然而，成因-核-地幔边界(CMB)的性质、空间范围、深度与中地幔过渡带(410-660公里深)--实际上，冰岛羽流的存在本身就是高度争论的问题。最近的地震学模型表明，地幔热柱可能从格陵兰岛下方升起，被北美构造板块底部的地形转向冰岛，并延伸到板块下方，直到不列颠群岛。由于全球数亿人的生活受到火山活动的影响，至关重要的是通过绘制地球表面以下的岩浆地图来了解是什么驱动了火山喷发，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(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屏障)之间的相互作用在地球上产生的自然电场和磁场来表征地球的导电结构。我建议在苏格兰、冰岛和格陵兰进行MT阵列测量，以补充现有的地震学数据。我制作的地幔3D电导率模型，以及电磁、地震和物理化学数据的联合反演，将明确解决与冰岛热点的性质有关的争议，这些争议无法用单一的地球物理方法来解决。现代社会必须在对能源的贪婪与减缓进一步人为排放温室气体的措施之间取得平衡。温室气体的进一步人为排放会推动气候变化。在英国，这一认识导致了海上风力发电的发展，并提议通过一种名为大西洋超级连接的高压电缆将地热发电的低碳电力从冰岛输送到英国大陆。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导致停电的风险，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，预计将大幅增加。空间天气被列入国家风险登记册，列为与中等影响社会经济风险有关的中高可能性事件，联合王国政府认识到需要提高预测极端空间天气事件及其对地面技术基础设施的影响的能力，以便能够制定缓解战略。风暴期间的磁场及其引发的GIC之间的比例，以及不同地理区域对磁暴的脆弱性，是由地球深层的3D导电结构决定的。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电场的估计、最坏情况下的空间天气危险地图和概率预报，尤其是从冰岛到英国的高压海底电缆。

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.