Explosive post-caldera collapse eruptions in the Kermadec-Tonga Arc

火山爆发作为海洋岛屿呈现出各种各样的直接和间接危害。Hunga Tonga-Hunga Ha'apai是一个沿kermade - tonga弧的海底崩塌火山口，具有一个活跃的陆上火山口边缘锥。2021年12月，Hunga Tonga-Hunga Ha'apai火山活动恢复，活动在西北火山口边缘锥形成了一个新的喷口。在2022年1月15日04:14 UTC，中央火山口喷口爆发了近30年来全球最强大的一次喷发。火山喷发产生了30公里高、4公里宽的火山灰柱、穿越地球大气层的气压波、6.5兆瓦的地震和跨洋海啸。与火山喷发有关的海底过程也切断了当地和国际海底电信电缆，导致协调救灾工作困难，有效地切断了汤加与国际通信的联系。火山喷发带来的连锁灾害造成了9040万美元的损失，相当于汤加国内生产总值的18.5%。从苏尔特采扬式喷发迅速升级为普林尼南式喷发并引发海啸，形成了地质灾害盲点。重要的是要了解喷发和层叠的危害。虽然这次喷发以其威力和连锁危害而闻名，但一个重要的问题是，在没有预警的情况下，爆炸性的升级仍然是一个主要问题。卫星证据表明，活跃的东北火山口边缘锥在喷发前不到两小时被摧毁，这就提出了一个更具体的问题，即它在喷发爆炸性升级中的作用。此外，克马德克-汤加弧由28个类似的塌陷火山口火山组成，因此一个重要的问题是，HT-HH的喷发是否可能代表整个克马德克-汤加弧的火山活动？该项目建议汇集多个学科的顶尖专家（包括火山学家、地球化学家、海洋沉积学家、海啸专家和技术专家）。该项目还利用了对多个不同的免费数据集的独特访问，这将使合作伙伴能够回答上述问题。为了解决这些重要问题，我们将在2022年4月和2022年8月与合作伙伴NIWA和GNS一起整理新获得的高分辨率多波束测深数据。将这些数据与2016年的测深数据进行比较，将使我们能够确定火山喷发引起的海底变化，计算火山喷发期间增加或移动的物质体积，并从绘制的地貌变化中得出火山喷发特征。这项研究提供了一个新的基线，未来对这种潜在的范式转移喷发的更大规模研究可以基于此，所产生的产品将有助于约束未来喷发和海啸建模的边界条件。来自类似环境（例如喀拉喀托火山）的证据表明，环境是难以置信的动态，因此该项目受益于火山爆发后尽快收集的数据。这个机会是独一无二的，因为活动的规模和研究的高质量数据（预先存在的水深测量、有线电视运营商的合作、严格限制的喷发时间和过程），还利用了延长附近预定的研究巡航的优势，大大降低了相关成本、二氧化碳排放量和国际合作伙伴的COVID-19风险。

Volcanic eruptions as ocean islands present a diverse range of direct and indirect hazards. Hunga Tonga-Hunga Ha'apai is a submarine collapse caldera along the Kermadec-Tonga arc with an active subaerial caldera rim cone. Volcanic activity renewed at Hunga Tonga-Hunga Ha'apai in December 2021 with activity developing a new vent at the NW caldera rim cone. At 04:14 UTC on January 15th 2022, the central caldera vent erupted with the most powerful eruption globally in the last 30 years. The eruption produced a 30 km-high and 4 km-wide ash column, barometric pressure waves that transited the Earth's atmosphere, a 6.5 MW earthquake and a trans-oceanic tsunami. Seafloor processes related to the eruption also severed local and international submarine telecommunication cables, which led to difficulties co-ordinating disaster response, effectively cutting off Tonga from international communications. The cascading hazards from the eruption caused $90.4M of damage, equivalent to 18.5% of Tonga's Gross Domestic Product. The eruption presented a geohazard blind spot in its rapid escalation from Surtseyan to Plininan-style eruption and generation of tsunami. It is important to understand the eruption and the cascading hazards. Whilst the eruption is notable for its power and cascading hazards, a significant question is the escalation in explosivity without warning remains a major question. Satellite evidence indicates that the active NE caldera rim cone was destroyed less than two hours before the eruption, posing a more specific question of its role in the escalation in eruption explosivity. Furthermore, the Kermadec-Tonga arc is populated by 28 similar collapse caldera volcanoes, thus an important question is whether the eruption at HT-HH likely representative of volcanism across the Kermadec-Tonga arc? This project proposes to bring together leading experts in multiple disciplines (including volcanologists, geochemists, marine sedimentologists, tsunami specialists and technologists). The project also utilises unique access to multiple different complimentary datasets that will allow the assembled partnership to answer these questions above.In order to address these important questions we will collate newly acquired high-resolution multibeam bathymetric data in April 2022 and August 2022 with partners NIWA and GNS. The comparison of this data with bathymetry from 2016 will allow us to identify seafloor changes caused by the eruption, calculate the volumes of material added or mobilised during this event, and derive eruption characteristics from the geomorphological changes mapped. This study provides a new baseline from which future larger studies of this potentially paradigm-shifting eruption can be based and the products generated will help to constrain the boundary conditions for future eruption and tsunami modelling. Evidence from similar settings (e.g. Anak Krakatau) indicate that the environment is incredibly dynamics, thus the project benefits from data collected as soon as is feasible after the eruption. This opportunity is unique both because of the scale of the event and because of the high-quality data available to study it (pre-existing bathymetry, cooperation from cable operators, well constrained eruption timings and processes) and also takes advantage of extending a scheduled research cruise nearby, significantly reducing the associated costs, CO2 outputs and COVID-19 exposure for international partners.