Taking Earth's volcanic pulse: understanding global volcanic hazards by unlocking the ice core archive

2022年初，太平洋岛屿上一座研究较少的火山Hunga Tonga-Hunga Ha apai爆发，其能量比投在广岛的原子弹大1000倍。这次喷发产生的波浪在地球周围回荡，并发出了高达55公里的火山羽，到达太空的一半。虽然这次火山爆发对汤加来说是毁灭性的，但幸运的是，从全球角度来看，它持续时间很短，而且没有发生在人口稠密的地区，也没有发生在重要的粮食生产、运输或能源传输地区。火山学家研究过去的火山事件，以便我们能够了解它们的重现期和影响，并帮助社会为下一次“大事件”做好准备。大规模的火山喷发会将大量的火山灰和气体排放到大气中，这些羽流经过区域和全球分布，可以从源头传播数千公里。在大多数地表环境中，细粒的火山沉降物很快就被冲走了。冰盖是个例外，通过钻冰和提取核心，科学家可以识别富硫层和火山灰沉积这些过去的爆发。虽然冰芯提供了过去火山活动无可争议的最佳档案，但解释这些记录并不简单，我们目前的技术几乎没有告诉我们源火山的位置以及它可能对气候产生的影响。即使在过去2500年的记录中，我们也只知道25次最大火山爆发中的7次。本项目将开发新的冰芯化学分析，以提取有关过去火山活动的来源，风格和环境影响的详细信息。它将利用最近在冰芯研究方面的两项突破。第一个是对火山硫进行高时间分辨率的化学分析，提供关于火山羽流在大气中达到的高度以及喷发源与冰盖的接近程度的关键信息。第二个是火山灰颗粒化学，它可以帮助确定火山的来源和环境。在该研究的第一阶段，我们验证了这些技术的知名喷发，我们已经有很好的信息，喷发源，风格和气候影响。我们建立了新的协议来分析火山灰的微小碎片（其中许多直径比一根人的头发还小），并开发出一种计算机模型，可以预测不同喷发风格的硫化学成分，使我们能够直接从冰芯指纹中推断出来源和气候影响，在这个项目的最后阶段，我们将运用我们的新技术来解开冰芯档案中最大喷发的来源和气候影响。其中许多是神秘的喷发，我们知道那里有大量的硫排放，但我们还不知道确切的火山源。了解这些巨大的神秘喷发的来源是火山学和古气候学的突出挑战之一，我们的技术无疑将为这些特殊事件提供迷人的见解，并激发火山学家，气候学家和历史学家之间的新互动。为了确保最大的影响，我们将把这些发现嵌入全球火山灾害数据库，供科学家、政府和工业界使用（例如，航空和保险），以量化过去火山爆发的规模，频率和风格，并改善对未来火山事件的预测。我们的工作将为过去火山爆发的气候影响提供基本见解，并将帮助科学家和政策制定者在地球仪上容易发生大规模火山事件的地区进行火山监测。最终，有了这些知识，我们将更好地为下一次“大灾难”做好准备，这将有助于限制生命损失，减少经济损失。

At the start of 2022, a little studied Pacific Island volcano, Hunga Tonga-Hunga Ha apai, erupted with an energy ~1000x greater than the atomic bomb dropped on Hiroshima. This eruption created waves that reverberated around the Earth and sent up a volcanic plume that reached ~55 km, half-way to space. Although this eruption was devastating for Tonga, mercifully, from a global perspective, it was short in duration and did not occur in a densely populated area or one of vital food production, transport, or energy transmission. Had it done so there would have been major impacts on climate and society.Volcanologists study past volcanic events so that we can understand their return periods and impacts and help prepare society for the next 'big one'. Large eruptions loft enormous quantities of ash and gas into the atmosphere, these plumes undergo regional and global distribution and can travel thousands of kilometres from their source. In most surface environments the fine-grained volcanic fallout is rapidly washed away. Ice sheets are the exception to this, and by drilling into the ice and extracting core scientists can identify the sulfur-rich layers and ash deposited by these past eruptions. Although ice cores provide the undisputed best archive of past volcanism, interpreting this record is not straightforward and our current techniques tell us little about where the source volcano was located and what its climate impact might have been. Even in records that span the last 2500 years, we only know the location of 7 of the 25 largest volcanic eruptions.This project will develop novel ice core chemical analyses to extract detailed information on the source, style, and environmental impacts of past volcanism. It will take advantage of two recent breakthroughs in ice core research. The first is high time resolution chemical analysis of volcanic sulfur which provide critical information about the height the volcanic plume reached in the atmosphere and the proximity of the eruptive source to the ice sheet. The second is ash particle chemistry which can help pinpoint the volcanic source and setting. During the first phase of this fellowship, we validated these techniques for well-known eruptions where we already have good information on the eruptive source, style and climatic impacts. We set up new protocols to analyse tiny fragments of ash (many of which are smaller in diameter than a human hair) and developed a computer model that can predict the sulfur chemistry for different eruption styles, allowing us to infer the source and climate impact directly from the ice core fingerprint.In the final phase of this project, we will apply our new techniques to unravel the source and climate impacts of the greatest eruptions in the ice core archive. Many of these are mystery eruptions, where we know there was a massive sulfur emission, but we don't yet know the exact volcanic source. Understanding the source of these massive mystery eruptions is one of the outstanding challenges in volcanology and paleoclimate, and our techniques will undoubtedly provide fascinating insights into these exceptional events and stimulate new interactions between volcanologists, climatologists, and historians.This project will provide critical new information about volcanism on Earth. To ensure maximum impact we will embed these findings in global volcanic hazard databases which will be used by scientists, governments, and industry (e.g., aviation and insurance) to quantify the magnitude, frequency and style of past eruptions and improve forecasts of future volcanic events. Our work will provide fundamental insights the climate impacts of past eruptions and will also help scientists and policy makers to target volcano monitoring in regions of the globe that are prone to large volcanic events. Ultimately, with this knowledge we will be better prepared for the next 'big one' and this will help limit the loss of life and reduce the economic losses.