Offshore hazard cascades from the largest volcanic eruption this century

本世纪最大规模的火山喷发造成近海灾害级联

• 批准号: NE/X00239X/1
• 负责人: Mike Clare
• 金额: $ 12.84万
• 依托单位: NATIONAL OCEANOGRAPHY CENTRE
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX00239X%2F1
• 关键词: Offshore; hazard; cascades; largest; volcanic

Volcanic eruptions in marine settings pose a diverse range of hazards, both directly and indirectly caused by the eruption. In January 2022 the partially-submerged Tongan volcano Hunga Tonga - Hunga-Ha'apai experienced one of the most powerful volcanic events seen in decades, generating a tsunami that caused damage both locally and on shorelines thousands of km away, breaking the only seafloor telecommunications cables that connect Tonga to the rest of the world and causing $90.4M of damage, equivalent to 18.5% of Tonga's Gross Domestic Product. The damage to the cable both severely hampered efforts to contact and assist Tonga in the immediate aftermath of the disaster and the time of writing (16th Feb 2022) had not yet been repaired; effectively meaning that 105,000 Tongan citizens have had to rely on low bandwidth, high latency satellite communication for over a month. Both the local tsunami and the cable break were unusual. First, while local tsunami waves ran up to 15m in some parts of Tonga, this near field tsunami was smaller and caused less damage than similar events elsewhere e.g. smaller 2018 Anak Krakatau volcanic-tsunami. Second, while the explosive event at the volcano occurred at 04:14 UTC the seabed cable faults did not occur until 05:40 UTC, 90 minutes later. This proposal will examine whether these events were caused by secondary submarine landslides or other process and will characterise their locations, dynamics and magnitudes. In order to address these important questions we will collect new high-resolution multibeam bathymetric data in April 2022 over the region to compare with existing high-resolution data from before the eruption. This comparison will allow us to identify seafloor changes caused by Hunga Tonga -Hunga Ha'apai, map their locations and extents and calculate the volumes of material added or mobilised during this event. This study will also provide 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 tsunami modelling. In order for data to be accurate and useful they must be collected as soon as is feasible after the eruption. The seafloor is extremely dynamic (as shown by repeat surveys at smaller offshore volcanoes), large volumes of material can be deposited over short timescales and existing shallow sediments can be remobilised by waves and storms. 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 and CO2 outputs. Cable companies can share data from the faults and repair, but their vessels are not equipped with multibeam sonars required to perform detailed seafloor surveys; hence the causes of faults, the nature of the eruptive event are unclear and cannot be addressed by satellite data either. Hunga Tonga-Hunga Ha'apai is far from unique; there are numerous similar volcanoes both in the Tofua Arc and worldwide. However, very few of these are monitored and most are poorly surveyed; hence the risk they pose is unclear. This timely project will provide the first detailed time-lapse surveys for such a large offshore eruption, and thus enables major step changes in understanding the dynamics of extremely large eruptions, and how they generate secondary hazards, via tsunami or breaking critical seabed telecommunication cables that carry >99% of all digital traffic globally. Time is of the essence; performing a rapid response survey (by extending an already scheduled cruise that will travel close to the area) will provide robust answers to fundamental questions about submarine volcanic eruptions and their linked hazards.

海洋环境中的火山喷发构成了多种危害，无论是由喷发而直接和间接引起的。 2022年1月，在2022年1月，汉田汤加（Hunga Tonga） - 洪加 - 哈帕（Hunga-Ha'apai）经历了数十年来最有强大的火山事件之一，产生了一场海啸，在当地和海岸线上造成了数千公里的损害，造成了数千公里的距离，使唯一的seafloor电信电信电信造成了汤加的唯一损害汤加（Tonga）的唯一损害。汤加的国内生产总值。电缆对电缆的损害都严重阻碍了在灾难发生后立即接触和协助汤加（2022年2月16日）的努力；有效地这意味着有105,000名汤加公民必须依靠一个多个月以上的低带宽，高潜伏期的卫星通信。当地的海啸和电缆断路都是不寻常的。首先，虽然当地海啸波在汤加的某些地区占15m，但这种近场海啸却较小，造成的伤害比其他地方的类似事件较小，例如较小的2018年Anak Krakatau火山 - 海湾。其次，尽管火山发生的爆炸事件发生在04:14 UTC，但直到90分钟后的05:40 UTC才发生海床电缆故障。该提案将检查这些事件是由次级海底滑坡还是其他过程引起的，并将表征其位置，动态和大小。为了解决这些重要问题，我们将在2022年4月在该地区收集新的高分辨率多冰止测深数据，以与喷发前的现有高分辨率数据进行比较。这种比较将使我们能够识别由Hunga Tonga -Hunga Ha'apai引起的海底变化，绘制其位置和范围，并计算此事件中添加或动员的材料量。这项研究还将提供一个新的基线，可以从该基线进行这种潜在范式转移喷发的未来更大的研究，并且生成的产品将有助于限制未来海啸建模的边界条件。为了使数据准确且有用，必须在爆发后尽快收集它们。海底是极具动态的（如较小的海上火山的重复调查所示），可以在短时间内沉积大量材料，现有的浅层沉积物可以通过波浪和暴风雨来重新启动。这个机会是独一无二的，这既是事件的规模，又是由于可供研究的高质量数据（预先存在的测深，有线电视操作员的合作，良好的爆发时间和过程），并且还利用了附近的预定研究巡航，从而大大降低了相关成本和CO2输出。有线电视公司可以从故障和维修中共享数据，但是它们的船只没有配备进行详细海底调查所需的多束声纳。因此，故障的原因，喷发事件的性质尚不清楚，也无法通过卫星数据来解决。 Hunga Tonga-Hunga Ha'apai远非独特。豆腐弧和全球都有许多类似的火山。但是，其中很少有人受到监测，并且大多数受到调查不佳。因此，他们的构成风险尚不清楚。这个及时的项目将为如此大的离岸爆发提供首次详细的延时调查，从而在理解非常大的喷发的动态方面进行重大步骤变化，以及它们如何通过海啸或破坏关键的海底电视连通电缆产生次要危害，全球范围> 99％的数字流量> 99％。时间至关重要；进行快速响应调查（通过扩展已经计划在该地区附近的已安排的巡航）将为有关海底火山喷发及其连接的危害提供强有力的答案。

项目成果

Pyroclastic density currents explain far-reaching and diverse seafloor impacts of the 2022 Hunga Tonga Hunga Ha'apai eruption

火山碎屑密度流解释了 2022 年洪加汤加洪加哈派喷发对海底的深远而多样的影响

• DOI: 10.21203/rs.3.rs-2395332/v1
• 发表时间: 2023
• 作者: Seabrook S

Climate change hotspots and implications for the global subsea telecommunications network

• DOI: 10.1016/j.earscirev.2022.104296
• 发表时间: 2023-01-19
• 期刊: EARTH-SCIENCE REVIEWS
• 影响因子: 12.1
• 作者: Clare，M. A.;Yeo，I. A.;Carter，L.
• 通讯作者: Carter，L.