Constraints on the tempo and magnitude of explosive volcanism: facilitating long-term ash fall hazard assessments

对爆发性火山活动的速度和强度的限制：促进长期火山灰坠落危险评估

• 批准号: MR/Y011767/1
• 负责人: Paul Albert
• 金额: $ 75.48万
• 依托单位: Swansea University
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FY011767%2F1
• 关键词: Constraints; tempo; magnitude; explosive; volcanism

Explosive volcanic eruptions have devastating impacts in near-vent areas where pyroclastic density currents can cause significant loss of life, yet the injection of large volumes of ash into the atmosphere and its subsequent dispersal over hundreds to thousands of kilometres, pose significant and far-reaching hazards. Ash fall is a severe and wide-ranging volcanic hazard; causing roof collapse, health (respiratory) and agricultural issues and wide-scale interruptions to essential infrastructure. Even ash emitted during moderately explosive eruptions can ground air traffic as was demonstrated by the 2010 Eyjafjallajökull eruption (Iceland). As such widespread volcanic ash dispersals present huge economic and societal costs. Disturbingly, 800 million people live within 100 km of active volcanoes globally, yet statistical studies of global eruption databases indicate significant under-recording of past volcanic eruptions deeper in time. For instance, this analysis would indicate up to 66% of VEI 5 eruptions, equivalent in scale to the 1980 Mount St Helens eruption, are missing within the geological record spanning the last 200,000 years. Our understanding of the magnitude and frequency of eruptions at a particular volcano is typically skewed to recent activities, because records of older eruptions are fragmentary often owing to erosion and/or burial by more recent eruptions. The better-preserved, shorter-term records, however, do not necessarily reflect the full range of volcanic activity, or variations in the tempo of activity. This is a major obstacle for long-term volcanic hazard assessments and hampers our ability to: i) determine changing eruption-rates through time, ii) evaluate magnitude-frequency relationships and iii) project the recurrence intervals of hazardous ash dispersals. This research has overcome this impasse by reconstruct comprehensive long-term records of explosive volcanism for volcanoes in southern and central Japan. This research exploits the under-utilised record of volcanic ash layers preserved in dense networks of marine and lake sediment cores away from the volcano. These continuous sediment sequences present unprecedented repositories of ash fall (preserved as visible and microscopic deposits), which are not susceptible to destructive near-source volcanic processes. Using state-of-the-art chemical 'fingerprinting' techniques, it is possible to pinpoint the volcanic source of the distal ash layers, whilst tracing these ash fall events across a network of cores provides the opportunity to computationally model and map past ash dispersals, and calculate eruption magnitudes. Integrating cutting-edge dating techniques (40Ar/39Ar/14C) to date the ash deposits, enables us to reveal the timing and tempo of past explosive eruptions at an individual volcano, and importantly determine the recurrence intervals of widespread hazardous volcanic ash dispersals from these volcanoes. Our research in south and central Japan has been successfully tackling eruption un-reporting and plugged the gaps in the eruption records of numerous volcanoes. In the next phase of our research we will expand the application of our methods to address the volcanoes of NE Japan and the Kurile Arc, utilising newly available marine cores from International Ocean Discovery Programme (IODP) and Japan Agency For Marine-Earth Sciences and Technology (JAMSTEC). In addition, using our ability to produce comprehensive eruption records, we will explore volcano-climate interactions. The distal volcanological records generated in this project will continue to be examined in partnership with those directly responsible for volcanic hazard assessments at individual volcanoes, and policy-makers working in the field.

火山喷发对火山喷发口附近地区造成毁灭性影响，火山碎屑密度流可能造成重大生命损失，但大量火山灰喷入大气并随后扩散数百至数千公里，造成重大而深远的影响。火山灰坠落是一种严重且范围广泛的火山灾害；会导致屋顶塌陷、健康（呼吸）和农业问题，甚至还会造成重要基础设施的大规模中断。 2010 年埃亚菲亚德拉冰盖火山喷发（冰岛）证明，中度爆炸性喷发期间排放的火山灰会导致空中交通中断。据统计，如此广泛的火山灰扩散造成了巨大的经济和社会成本，令人不安的是，全球有 8 亿人生活在活火山周围 100 公里范围内。对全球喷发数据库的研究表明，过去的火山喷发在更深层的记录严重不足，例如，分析表明，在过去 20 万年的地质记录中，高达 66% 的 VEI 5 喷发（规模相当于 1980 年圣海伦斯火山喷发）缺失。通常偏向于最近的活动，因为较早的喷发记录往往是由于最近喷发的侵蚀和/或掩埋而变得零散，然而，保存较好的短期记录。不一定反映火山活动的全部范围，或活动节奏的变化，这是长期火山灾害评估的主要障碍，并妨碍我们：i）确定随时间变化的喷发率，ii）评估。本研究通过重建日本南部和中部火山喷发的长期记录，克服了这一僵局。火山灰层的未充分利用记录保存在远离火山的密集海洋和湖泊沉积物核心网络中，这些连续的沉积序列呈现出前所未有的火山灰沉积库（以可见和微观沉积物的形式保存），不易受到破坏性的影响。使用最先进的化学“指纹”技术，可以查明远端火山灰层的火山源，同时通过网络追踪这些火山灰掉落事件。岩心提供了对过去火山灰扩散进行计算建模和绘制地图的机会，并结合尖端测年技术 (40Ar/39Ar/14C) 来计算火山灰沉积物的年代，使我们能够揭示过去火山喷发的时间和速度。我们在日本南部和中部的研究已经成功地阻止了火山爆发的未报告和喷发。填补了众多火山喷发记录中的空白 在下一阶段的研究中，我们将利用国际海洋发现计划 (IODP) 新提供的海洋核心，扩大我们的方法的应用范围，以解决日本东北部和千岛弧的火山问题。 ）和日本海洋地球科学技术机构（JAMSTEC）此外，我们将利用我们生成综合喷发记录的能力，继续探索该项目中生成的远端火山记录。与直接负责各个火山的火山灾害评估的人员以及在该领域工作的政策制定者合作进行审查。