Collaborative Research: Linking 3He/4He with eruptive behavior: A time series analysis of recent Kilauea, Iceland, and La Palma eruptions

大约有8亿人生活在直接暴露在火山灾害中的地区，但火山喷发仍然难以预测。在某些情况下，地震和地面膨胀被用来预测即将爆发的火山喷发。在其他情况下，火山气体排放的变化被用来推断火山活动的变化，因为气体排放被认为与火山喷发前火山下方岩浆的上升有关。该项目探索了火山气体化学可能掌握有关岩浆补给的重要线索的可能性，这些线索可能有助于预测火山喷发的开始和过程。来自地球深处的岩浆富含3He(一种氦的同位素，与4He相比非常稀有)。因此，岩浆补给事件可能导致~3He相对于~4He的增加(即更高的~3He/~4He)。这一假设将通过测量最近在夏威夷、冰岛和加那利群岛喷发的熔岩中的3He/4He值来验证。通过将3He/4He与其他火山指标进行比较，包括熔岩排放量、熔岩成分、地震频率和震级，以及卫星探测到的火山气体的其他化学特征，研究小组将试图将3He/4He的变化与火山活动联系起来。如果氦系统因潜在危险的火山过程而发生变化，那么对火山进行实时氦监测可能是合理的。这个项目不仅旨在扩大我们对火山系统的了解，还强调高中、本科生和研究生教育。科学小组将与马萨诸塞州布罗克顿的新高地特许学校合作，开展与火山学有关的讲座和活动。伍兹霍尔海洋研究所的两名本科生暑期研究员将从纽约城市大学(CUNY)招聘，该校拥有多元化的学生群体。另外两名纽约州立大学本科生将通过开展独立学习项目参与其中。一名参加麻省理工学院-伍兹霍尔海洋研究所联合项目的研究生将为研究的所有阶段做出贡献。这项工作将通过一个促进残疾人康复的伙伴组织为自闭症妇女提供就业机会。火山灾害预测仍然是火山学社区面临的一项紧迫而难以捉摸的挑战。地震活动和地面形变监测往往很难与岩浆作用联系起来。综合监测方法显示出最有希望的前景，特别是那些用地球化学监测补充现有技术的方法。氦同位素在这方面显示出巨大的潜力，因为它们(1)对补给事件很敏感，(2)可以在喷发期间和休息期在喷发期间和休息期进行监测--在喷发期间、土壤、地热水和熔岩中。此外，前人的工作表明，氦同位素(3He/4He)对来自地幔的岩浆补充事件很敏感。该项目的目标是在几周到几个月的时间尺度上评估3He/4He变化的原因，以确定昂贵的实时氦同位素监测工作是否将改善火山灾害预测。这项研究将产生最近三次喷发的岩浆3He/4He时间序列记录：夏威夷Kī劳厄下部裂谷带(2018年)、冰岛的Fagradalsfjall(2021年)和加那利群岛的坎布雷·维亚(2021年)。岩浆氦将从单斜辉石中提取，橄榄石矿物将从每次喷发的熔岩样本中分离出来。对熔岩3He/4He、主元素和微量元素丰度、放射性同位素和遥感数据--包括地面变形、地震活动、卫星SO2排放和熔岩排放率--的比较将确定岩浆补给是否是3He/4He变化的主要原因。或者，源不均质性或岩石圈氦同化作用可能占主导地位。通过调查多个监测良好的喷发，该项目可能会确定火山喷发期间氦同位素变化的常见原因。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Approximately 800 million people live in regions that are directly exposed to volcanic hazards, yet eruptions remain difficult to forecast. In some cases, earthquakes and ground swelling have been used to predict imminent volcanic eruptions. In other instances, changes in volcanic gas emissions have been used to infer changes in volcanic activity because gas emissions are thought to be linked to the ascent of magmas beneath volcanoes preceding eruptions. This project explores the possibility that volcanic gas chemistry might hold vital clues about magma recharge that could help forecast the onset and course of volcanic eruptions. Magmas from the deep Earth are rich in 3He (an isotope of helium that is very rare compared to 4He). Thus, magma recharge events may cause increases in 3He relative to 4He (i.e., higher 3He/4He). This hypothesis will be tested by measuring 3He/4He values in lavas from recent eruptions in Hawai’i, Iceland, and the Canary Islands. By comparing 3He/4He to other volcanic indicators, including lava discharge rate, lava composition, earthquake frequency and magnitude, and other chemical features of volcanic gases detected by satellites, the team will attempt to link changes in 3He/4He to volcanic activity. If helium systematics change in response to potentially hazardous volcanic processes, real-time helium monitoring of volcanoes may be justified. Not only does this project aim to broaden our understanding of volcanic systems, it also emphasizes high school, undergraduate, and graduate education. In partnership with the New Heights Charter School, in Brockton Massachusetts, the science team will develop lectures and activities relating to volcanology. Two undergraduate summer student fellows at Woods Hole Oceanographic Institution will be recruited from City University of New York (CUNY), which has a diverse student population. Two additional CUNY undergraduate students will participate by conducting independent study projects. One graduate student enrolled in the Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program will contribute to all stages of the research. And this work will provide employment for an autistic woman through a partner organization that facilitates rehabilitation for individuals with disabilities.Volcanic hazard forecasting remains a pressing and elusive challenge for the volcanology community. Seismic activity and ground deformation monitoring are often difficult to link with magmatic processes. Integrative monitoring approaches show the most promise, especially those that supplement established techniques with geochemical monitoring. Helium isotopes show great potential in this regard because they (i) are sensitive to recharge events and (ii) can be monitored—in fumaroles, soils, geothermal waters, and lavas—during eruptions and during periods of repose. Furthermore, previous work indicates that helium isotopes (3He/4He) are sensitive to magma recharge events from the mantle. The goal of this project is to assess the causes of 3He/4He variability on timescales of weeks to months in order to determine whether costly real-time helium isotope monitoring efforts would improve volcanic hazard forecasting. This study will produce magmatic 3He/4He time series records for three recent eruptions: the Lower Eastern Rift Zone of Kīlauea in Hawaii (2018), Fagradalsfjall in Iceland (2021), and Cumbre Vieja in the Canary Islands (2021). Magmatic helium will be extracted from clinopyroxene and olivine mineral separates from lava samples spanning each eruption. Comparison of lava 3He/4He, major and trace element abundances, radiogenic isotopes, and remote sensing data—including ground deformation, seismicity, satellite-based SO2 emissions, and lava discharge rates—will establish whether magma recharge is principally responsible for 3He/4He variability. Alternatively, source heterogeneity or lithospheric helium assimilation might be dominant. By investigating multiple well-monitored eruptions, this project will potentially identify common causes of helium isotopic variability during volcanic eruptions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.