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，而且许多滑坡会产生破坏性的海啸。挪威近海的斯托雷加滑道覆盖的面积比苏格兰还大，含有的沉积物足以覆盖整个苏格兰，深达80米。这一巨大的滑行发生在8200年前，向下延伸800公里。它引发了一场海啸，挪威海周围20米，苏格兰本土3-8米。英国几乎没有面临其他自然灾害，可以造成像斯托雷加滑行海啸那样规模的破坏。斯托雷加滑梯并不是挪威海中唯一的大型潜艇滑梯。已公布的数据表明，在过去的2万年里，至少有6次这样的幻灯片。例如，Traenadppet滑移发生在4000年前，涉及约900千米的沉积物。根据4,000年的重复间隔(过去8,000年中有2次事件，或20,000年中有6次事件)，在未来200年内发生重大海底滑坡和可能发生海啸的可能性为5%。设得兰的沉积沉积物年代为1500年和5500年，除了8200年的Storegga沉积物外，还被认为表明海啸的影响，并提供证据表明北极海啸的危害仍未得到充分了解。鉴于北极山体滑坡引发的海啸的潜在影响，我们需要严格评估它们在未来100-200年内对英国构成的危险，它们对社会的潜在成本，现有的海防在多大程度上保护英国，以及如何将海啸灾害纳入多种灾害的洪水风险管理。这个项目是及时的，因为北极的快速气候变化可能会增加滑坡-海啸带来的风险。与未来冰川融化相关的地壳反弹可能会产生更大、更频繁的地震，例如可能在8200年前触发了斯托雷加滑动。据预测，北极在未来几十年还将经历特别迅速的变暖，这可能会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)解离，削弱沉积物，并可能增加滑坡的风险。我们的目标将通过一系列综合工作块来实现，这些工作块检查挪威海最近地质记录中保存的山体滑坡的频率、设得兰相关的海啸沉积物、冰川融化引起的地震频率和规模的未来趋势、山体滑坡引发的斜坡稳定性和海啸、英国的海啸淹没以及潜在的社会成本。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，到预测未来可能发生的山体滑坡和相关海啸的后果并计算其成本。将特别注意社会影响和缓解战略，包括审查目前海上防御的有效性。这将通过项目开始时利益相关者的参与来实现，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：(I)更好地了解过去北极山体滑坡的频率和海啸对英国的影响(Ii)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引起海啸，而其他山体滑坡不会。(Iii)单一的建模策略，从滑坡-海啸源耦合开始，跟踪海啸在挪威海的传播，以英国海岸被洪水淹没结束。将对不同规模和来源的海啸源进行测试(Iv)对海啸洪水对英国造成的后果和社会代价进行详细评估，包括现有防洪措施的有效性(V)评估气候变化可能如何改变滑坡频率，从而改变对英国的海啸风险。

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.