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

2022年初，太平洋上一座名为Hunga Tonga-Hunga Ha apai的火山爆发，其能量是投在广岛的原子弹的1000倍。这次喷发产生的波在地球周围回荡，喷出的火山羽流高达55公里，到达了太空的一半。虽然这次喷发对汤加是毁灭性的，但幸运的是，从全球的角度来看，它持续的时间很短，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、运输或能源输送地区。如果这样的话，将会对气候和社会产生重大影响。火山学家研究过去的火山事件，这样我们就可以了解它们的回归期和影响，并帮助社会为下一次“大火山”做好准备。大规模的喷发将大量的火山灰和气体抛入大气，这些羽状物分布在区域和全球，可以从源头传播数千公里。在大多数地表环境中，细颗粒的火山沉降物会被迅速冲走。冰盖是一个例外，通过在冰层上钻孔并提取核心，科学家们可以识别出过去火山喷发沉积的富含硫层和火山灰。虽然冰芯提供了无可争议的过去火山活动的最佳档案，但解释这些记录并不直截了当，而且我们目前的技术几乎不能告诉我们火山源的位置以及它可能对气候造成的影响。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次的位置。该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、类型和环境影响的详细信息。它将利用冰芯研究的两个最新突破。首先是火山硫的高时间分辨率化学分析，它提供了关于火山柱在大气中达到的高度和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。在研究的第一阶段，我们对已知的火山爆发进行了验证，我们已经掌握了火山爆发的来源、喷发方式和气候影响的良好信息。我们建立了新的协议来分析微小的火山灰碎片（其中许多碎片的直径比人类的头发还小），并开发了一个计算机模型，可以预测不同喷发风格的硫化学，使我们能够直接从冰芯指纹推断来源和气候影响。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火山爆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来源。了解这些大规模神秘喷发的来源是火山学和古气候学中最突出的挑战之一，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。这个项目将提供有关地球上火山活动的重要新信息。为了确保产生最大的影响，我们将把这些发现嵌入全球火山灾害数据库，供科学家、政府和行业（如航空和保险）使用，以量化过去火山爆发的震级、频率和类型，并改进对未来火山事件的预测。我们的工作将为过去火山爆发对气候的影响提供基本的见解，也将帮助科学家和政策制定者在全球容易发生大型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“大地震”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.