Virunga Volcanic SO2 Emissions Research (VISOR) Project

非弧火山的二氧化硫（SO2）排放构成了全球火山硫收支的重要组成部分，并且被认为与喷发的熔岩体积（即没有多余的硫）成正比。然而，迄今为止，证明这一点的努力很少，特别是对于碱性火山。该项目将结合遥感和岩石学分析，调查位于刚果民主共和国东非裂谷西部维龙加地区的活火山尼亚穆拉吉拉火山和尼拉贡戈火山的二氧化硫排放的起源和动态。尼亚穆拉吉拉火山和尼拉贡戈火山都是巨大的硫排放者，前者是在频繁的喷发中产生的，而后者则是自2002年以来通过持续的被动脱气产生的。到目前为止，还没有一致的尝试将这些二氧化硫的排放与岩浆的产生联系起来，或者调查异常二氧化硫输出的起源。VISOR项目的主要组成部分是：(1)分析1978年以来若干仪器收集的卫星数据，以建立维龙加火山最近二氧化硫排放的完整记录。还将绘制最新的熔岩流地图；(2)在刚果民主共和国进行实地考察，与戈马火山观测站（GVO）的刚果科学家合作，在尼拉贡戈进行SO2地面监测，包括测量SO2排放，并与GVO及其合作者收集的其他火山学数据集一起对数据进行解释。将通过比较基于现场和卫星的一致二氧化硫测量值来验证卫星测量值；(3)对Nyamuragira和Nyiragongo历史喷发产物中挥发物浓度和形态进行岩石学分析，确定喷发期间岩浆脱气的程度。这些数据将与遥感二氧化硫测量数据相结合，以评估一系列喷发事件中熔融硫损失与测量二氧化硫产量之间的关系；因此，对非弧形碱性火山过量硫排放的发生率以及碱性玄武岩岩浆中硫和其他挥发物的行为有了新的认识。本研究的更广泛影响包括：加强美国、非洲和欧洲群体之间的国际合作联系；对一名女研究生进行遥感、岩石学技术和实地考察方面的培训；多年来遭受忽视和内乱的GVO为非洲科学家提供了宝贵的专业知识和合作活动；利用为该项目获得的卫星数据在戈马开展外联项目；并将外来的火山岩成分添加到史密森学会的国家岩石收藏档案中，以供未来的研究工作。

Sulfur dioxide (SO2) emissions from non-arc volcanoes constitute a significant component of the global volcanic sulfur budget, and have been assumed to scale directly with erupted lava volume (i.e. that there is no excess sulfur). However, to date there have been very few efforts to prove this, particularly for alkaline volcanoes. This project will merge remote sensing and petrological analysis to investigate the origins and dynamics of SO2 emissions from Nyamuragira and Nyiragongo, the active, alkaline volcanoes in the Virunga region of the western arm of the East African Rift in DR Congo. Both Nyamuragira and Nyiragongo are prodigious sulfur emitters, the former during its frequent effusive eruptions and the latter via persistent passive degassing since 2002. To date there has been no concerted attempt to link these SO2 emissions with magma production, or to investigate the origin of the exceptional SO2 output. The main components of the VISOR project are: (1) Analysis of satellite data collected by several instruments since 1978 to develop a complete record of recent SO2 emissions from the Virunga volcanoes. An up-to-date map of recent lava flows will also be constructed; (2) Fieldwork in DR Congo to collaborate with Congolese scientists at the Goma Volcano Observatory (GVO) on ground-based SO2 monitoring at Nyiragongo, including measurement of SO2 emissions and interpretation of the data alongside other volcanological datasets collected by GVO and collaborators. Validation of satellite measurements will be achieved by comparing coincident field- and satellite-based SO2 measurements; (3) Petrological analyses of volatile concentrations and speciations in historical eruptive products of Nyamuragira and Nyiragongo to determine the extent of magma degassing during eruptions. These data will be combined with the remotely sensed SO2 measurements to assess the relationship between melt sulfur loss and measured SO2 production for a series of eruptive events; thus shedding new light on the incidence of excess sulfur emissions at non-arc, alkaline volcanoes, and into the behavior of sulfur and other volatiles in alkali-basaltic magmas. Broader impacts of this study include: strengthening of international collaborative links between groups in the USA, Africa, and Europe; training of a female graduate student in remote sensing, petrological techniques and fieldwork; a valuable infusion of expertise and collaborative activity for African scientists at GVO, which has suffered many years of neglect and civil unrest; outreach projects in Goma using satellite data acquired for the project; and the addition of exotic volcanic rock compositions to the National Rock Collection archive at the Smithsonian Institution, for future research efforts.