Virunga Volcanic SO2 Emissions Research (VISOR) Project

来自非弧火山的二氧化硫（SO2）排放构成了全球火山硫预算的重要组成部分，并被认为与喷发的熔岩量直接相关（即没有过量的硫）。然而，到目前为止，很少有努力证明这一点，特别是碱性火山。该项目将把遥感和岩石学分析结合起来，调查刚果东非大裂谷西臂维龙加地区的Nyamuragira和Nyiragongo两座碱性活火山的二氧化硫排放的来源和动态。Nyamuragira和Nyiragongo都是巨大的硫排放者，前者在其频繁的喷发期间，后者自2002年以来通过持续的被动脱气。到目前为止，还没有一致的尝试将这些二氧化硫排放与岩浆生产联系起来，或调查异常二氧化硫排放的起源。VISOR项目的主要组成部分是：（1）分析自1978年以来由几种仪器收集的卫星数据，以便对维龙加火山最近的二氧化硫排放量进行完整记录。还将绘制最新的熔岩流地图;（2）在刚果民主共和国开展实地工作，与戈马火山观测站的刚果科学家合作，在尼拉贡戈进行基于地面的二氧化硫监测，包括测量二氧化硫排放量，并对数据以及全球观测站和合作者收集的其他火山学数据集进行解释。将通过比较同时进行的实地和卫星SO2测量来验证卫星测量结果;（3）对Nyamuragira和Nyiragongo历史喷发产物中的挥发性浓度和物种进行岩石学分析，以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相结合，以评估一系列喷发事件的熔融硫损失和测得的二氧化硫产量之间的关系;从而揭示了非弧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。这项研究的更广泛影响包括：加强了美国、非洲和欧洲各团体之间的国际合作联系;对一名女研究生进行了遥感、岩石学技术和实地考察方面的培训;为多年来受到忽视和内乱的GVO的非洲科学家注入了宝贵的专门知识和开展了合作活动;利用为该项目获得的卫星数据在戈马开展了推广项目;以及将外来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.