Will climate change in the Arctic increase the landslide-tsunami risk to the UK?

海底滑坡可能比陆地滑坡大得多，而且许多会产生破坏性的海啸。挪威近海的Storegga Slide覆盖的面积比苏格兰还大，所含的沉积物足以覆盖整个苏格兰，深度为80米。这次巨大的滑坡发生在8,200年前，向下延伸了800公里。它在挪威海周围产生了一场超过20米的海啸，在苏格兰大陆产生了3-8米的海啸。英国面临的其他自然灾害很少，可能会造成破坏的规模重复斯托雷加幻灯片海啸。Storegga Slide并不是挪威海唯一一个巨大的海底滑坡。公布的数据表明，在过去的20,000年中至少有六次这样的幻灯片。例如，Traenadjupet滑坡发生在4,000年前，涉及约900立方公里的沉积物。根据4,000年的重现间隔（过去8,000年发生2次事件，或20,000年发生6次事件），在未来200年内发生重大海底滑坡和可能的海啸的概率为5%。除了8200年的Storegga存款，设得兰群岛的沉积物可以追溯到1500年和5500年，被认为表明海啸的影响，并提供证据表明北极海啸的危险仍然知之甚少。考虑到北极滑坡产生的海啸的潜在影响，我们需要对它们在未来100-200年对英国造成的危险进行严格的评估，它们对社会的潜在成本，现有的海防保护英国的程度，以及如何将海啸灾害纳入多灾害洪水风险管理。该项目是及时的，因为北极地区的快速气候变化可能会增加滑坡海啸造成的风险。与未来冰融化相关的地壳反弹可能会产生更大和更频繁的地震，例如可能引发8200年前的Storegga Slide。预计北极在未来几十年内也将经历特别迅速的变暖，这可能导致海洋沉积物中的天然气水合物（甲烷和水的冰状化合物）分解，削弱沉积物并可能增加滑坡风险。我们的目标将通过一系列综合的工作块来实现，这些工作块检查了最近地质记录中保存的挪威海滑坡频率、设得兰群岛相关的海啸沉积物、由于冰融化导致的地震频率和规模的未来趋势、滑坡引起的边坡稳定性和海啸、英国的海啸淹没和潜在的社会成本。这形成了一个工作流程，从观察过去的山体滑坡开始，通过对其后果进行建模来预测和计算未来潜在山体滑坡和相关海啸的后果。将特别关注社会影响和缓解战略，包括审查目前海防的有效性。这将通过从项目一开始就让利益相关者参与来实现，包括管理英国洪水风险的政府机构、负责海啸预警系统的国际机构以及再保险部门。主要成果将是：（一）更好地了解过去北极山体滑坡的频率和由此产生的海啸对英国的影响（二）改进海底山体滑坡和相关海啸的模型，帮助理解为什么某些山体滑坡会导致海啸，而其他人不会。(iii)一个单一的建模策略，开始与耦合滑坡海啸源，跟踪整个挪威海的海啸传播，并与英国海岸的淹没结束。将测试各种规模和起源的海啸源（iv）详细评估海啸洪水对英国的后果和社会成本，包括现有防洪措施的有效性（v）评估气候变化如何改变滑坡频率，从而改变英国的海啸风险。

Submarine landslides can be far larger than terrestrial landslides, and many generate destructive tsunamis. The Storegga Slide offshore Norway covers an area larger than Scotland and contains enough sediment to cover all of Scotland to a depth of 80 m. This huge slide occurred 8,200 years ago and extends for 800 km down slope. It produced a tsunami with a run up >20 m around the Norwegian Sea and 3-8 m on the Scottish mainland. The UK faces few other natural hazards that could cause damage on the scale of a repeat of the Storegga Slide tsunami. The Storegga Slide is not the only huge submarine slide in the Norwegian Sea. Published data suggest that there have been at least six such slides in the last 20,000 years. For instance, the Traenadjupet Slide occurred 4,000 years ago and involved ~900 km3 of sediment. Based on a recurrence interval of 4,000 years (2 events in the last 8,000 years, or 6 events in 20,000 years), there is a 5% probability of a major submarine slide, and possible tsunami, occurring in the next 200 years. Sedimentary deposits in Shetland dated at 1500 and 5500 years, in addition to the 8200 year Storegga deposit, are thought to indicate tsunami impacts and provide evidence that the Arctic tsunami hazard is still poorly understood.Given the potential impact of tsunamis generated by Arctic landslides, we need a rigorous assessment of the hazard they pose to the UK over the next 100-200 years, their potential cost to society, degree to which existing sea defences protect the UK, and how tsunami hazards could be incorporated into multi-hazard flood risk management. This project is timely because rapid climatic change in the Arctic could increase the risk posed by landslide-tsunamis. Crustal rebound associated with future ice melting may produce larger and more frequent earthquakes, such as probably triggered the Storegga Slide 8200 years ago. The Arctic is also predicted to undergo particularly rapid warming in the next few decades that could lead to dissociation of gas hydrates (ice-like compounds of methane and water) in marine sediments, weakening the sediment and potentially increasing the landsliding risk. Our objectives will be achieved through an integrated series of work blocks that examine the frequency of landslides in the Norwegian Sea preserved in the recent geological record, associated tsunami deposits in Shetland, future trends in frequency and size of earthquakes due to ice melting, slope stability and tsunami generation by landslides, tsunami inundation of the UK and potential societal costs. This forms a work flow that starts with observations of past landslides and evolves through modelling of their consequences to predicting and costing the consequences of potential future landslides and associated tsunamis. Particular attention will be paid to societal impacts and mitigation strategies, including examination of the effectiveness of current sea defences. This will be achieved through engagement of stakeholders from the start of the project, including government agencies that manage UK flood risk, international bodies responsible for tsunami warning systems, and the re-insurance sector. The main deliverables will be:(i) better understanding of frequency of past Arctic landslides and resulting tsunami impact on the UK(ii) improved models for submarine landslides and associated tsunamis that help to understand why certain landslides cause tsunamis, and others don't.(iii) a single modelling strategy that starts with a coupled landslide-tsunami source, tracks propagation of the tsunami across the Norwegian Sea, and ends with inundation of the UK coast. Tsunami sources of various sizes and origins will be tested (iv) a detailed evaluation of the consequences and societal cost to the UK of tsunami flooding , including the effectiveness of existing flood defences(v) an assessment of how climate change may alter landslide frequency and thus tsunami risk to the UK.