Collaborative Research: Physical Modeling of Submarine Volcanic Eruption Generated Tsunamis

海啸通常与俯冲带上的海底地震有关，例如2011年的日本海啸。然而，有大量的海啸来源与海底火山喷发有关。火山海啸和构造海啸一样，通常在没有任何预警的情况下发生，会摧毁距离火山相当远的人口稠密的沿海地区。在过去250年里，发生了90多次火山海啸，约占所有直接由火山喷发造成的死亡人数的25%。过去300年中最致命的两次非构造性海啸是由于1883年印度尼西亚喀拉喀托火山喷发和相关的火山碎屑流，以及1792年日本温岑火山熔岩穹顶坍塌。在震源，火山海啸的波高可以超过构造海啸，但这些火山海啸会随着传播距离的增加而受到显著的波衰减和弥散。火山引发海啸至少有九种不同的机制。大多数火山海啸波是由海底或近水面环境中能量极高的爆炸性火山喷发，或由大量火山碎屑流或碎片雪崩流入海洋而产生的。最近于2015年7月在加勒比海格拉纳达附近的珍妮海底火山启动时发出的“橙色”警报，突显了确定潜在海底火山喷发的海啸波特征方面的挑战。在这项工作中，我们将进行一系列实验和紧密联系的建模工作，以量化震源喷发机制和波浪产生之间的关系。这项研究将服务于火山和海啸耦合危险的评估和缓解。这项研究的最终长期目标是通过海底火山喷发、海啸的产生和传播以及潜在的吞没和火山口形成的混合模拟来改变对海底火山海啸危险的评估和缓解。文献中缺乏与这些海底海啸产生过程有关的至关重要的数据。这项研究将通过对3D海底火山喷发海啸生成情景的混合建模来弥补缺失的数据。它将重点关注海底火山喷发和吞没造成的海啸。计算机控制的气动海底火山喷发海啸发生器(SVE-TG)将允许进行全3D物理建模。SVE-TG的可变喷发速度模拟了相对缓慢的泥火山和快速的爆炸性喷发。事件分析将用于确定SVE-TG的实验计划和设计，这将扩大现有NHERI海啸设施的能力。该实验计划将确定动态喷发柱的特征以及耦合的海啸产生、传播和潜在的火山口形成。海底火山喷发的综合实验结果将为海底火山喷发和吞没的数值模型提供强有力的验证工具。从目前的实验和数值研究来看，海底火山喷发事件的震源特征仍然很难受到约束。历史事件将通过描述的火山物质流动、喷发和海啸的耦合机制来模拟。这项研究将改变对海底火山海啸的认识和理解，并有可能减轻一些最致命的非构造海啸灾害。

Tsunamis are normally associated with submarine earthquakes along subduction zones, such as the 2011 Japan tsunami. However, there are significant tsunami sources related to submarine volcanic eruptions. Volcanic tsunamis, like tectonic tsunamis, typically occur with little warning and can devastate populated coastal areas at considerable distances from the volcano. There have been more than 90 volcanic tsunamis accounting for about 25% of all fatalities directly attributable to volcanic eruptions during the last 250 years. The two deadliest non-tectonic tsunamis in the past 300 years are due to the 1883 Krakatoa eruption in Indonesia with associated pyroclastic flows and Japan's Mount Unzen lava dome collapse in 1792. At the source, volcanic tsunamis can exceed tectonic tsunamis in wave height, but these volcanic tsunamis are subject to significant wave attenuation and dispersion with propagation distance. There are at least nine different mechanisms by which volcanoes produce tsunamis. Most volcanic tsunami waves have been produced by extremely energetic explosive volcanic eruptions in submarine or near water surface settings, or by flow of voluminous pyroclastic flows or debris avalanches into the sea. The recent "orange" alert in July 2015 at the Kick 'em Jenny submarine volcano off Granada in the Caribbean Sea highlighted the challenges in characterizing the tsunami waves for a potential submarine volcanic eruption. In this work we will conduct a suite of experiments and closely linked modeling efforts to quantify the relationship between source eruptive mechanism and wave generation. This research will serve assessment and mitigation of coupled volcanic and tsunami hazards.The ultimate long-term goal of this research is to transform assessment and mitigation of the submarine volcanic tsunami hazard through hybrid modeling of submarine volcanic eruption, tsunami generation and propagation along with the potential engulfment and caldera formation. Critically important data related to these submarine tsunami generation processes is lacking in the literature. This research will compensate for missing data by hybrid modeling of 3D submarine volcanic eruption tsunami generation scenarios. It will focus on the tsunami generation by submarine volcanic eruptions and engulfments. A computer controlled pneumatic submarine volcanic eruption tsunami generator (SVE-TG) will allow fully 3D physical modeling. The variable eruption velocities of the SVE-TG mimick relatively slow mud volcanoes and rapid explosive eruptions. The event analysis will be used to determine the experimental program and the design of the SVE-TG, which will expand the capabilities of the existing NHERI tsunami facilities. The experimental program will determine the characteristics of the dynamic eruptive column and the coupled tsunami generation, propagation and potential caldera formation. The combined experimental results from the submarine volcanic eruption will provide a robust validation tool for numerical models of submarine volcanic eruptions and engulfments. Source characteristics from submarine volcanic eruption events remain poorly constrained from present experimental and numerical studies. A historical event will be simulated by using described coupled volcanic mass flow, eruption and tsunami mechanisms. This research will transform knowledge and understanding of submarine volcanic tsunamis and potentially mitigate some of the deadliest non-tectonic tsunami hazards.