The excess gas paradox at volcanoes: does CO2 favor gas accumulation in mafic magmas?

火山喷发的预测对于全世界居住在火山附近的约11亿人来说至关重要，而且仍然具有相当大的挑战性。火山学家努力预测喷发的可能性、大小和类型。许多火山喷发释放出的过量火山气体比喷发的岩浆数量还要多。我们不了解控制岩浆中气体滞留和释放之间竞争的因素，这反过来又影响火山喷发的方式。该小组将通过研究在爆炸性喷发期间喷发的火山岩的孔隙度与通过对意大利埃特纳火山(Mt Etna)进行地面测量而监测到的火山气体排放化学之间的潜在联系来寻求答案。大约有100万人居住在火山喷口30公里以内。该项目将支持一名博士生和一名本科生。研究成果将在出版物、公开讲座、大学网站、社交媒体和公共大众媒体上分享。该项目旨在弥合火山观测站收集的数据和分析与对岩浆物理学不断加深的了解之间的差距，特别是在挥发性气体物种在控制喷发行为方面的关键作用的背景下。该项目的目标是将动乱阶段岩浆中喷发前到喷发时的孔隙度与活火山的气体排放联系起来。PI计划通过检验两个假设来解决意大利埃特纳火山喷发出的火山气体和喷发的岩浆之间的体积差异，埃特纳火山是世界上监测和研究最好的火山之一：1)气体中二氧化碳浓度的增加有利于镁铁质岩浆孔隙度的增加；2)用于确定深层镁铁质岩浆孔隙度的气体排放中的二氧化碳/二氧化硫。该项目包括三项任务来验证所提出的假设：a)埃特纳山典型喷发的火山样品的详细显微结构和地球化学特征，b)埃特纳山喷发类型、强度和强度等岩浆孔隙度和火山参数的时间综合分析，以及c)利用现有的溶解度模型模拟喷发前和协同条件下镁铁质岩浆中H2O、CO2和S在硅酸盐熔体和出溶气相之间的分配。该项目包括与意大利国家地质与火山研究所(INGV)和德国汉堡DESY同步加速器设施的科学家合作。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The forecasting of volcanic eruptions is vital for ~1.1 billion people living near volcanoes worldwide, and remains quite challenging. Volcanologists strive to forecast the likelihood, size, and style of eruptions. Many eruptions emit an excess amount of volcanic gases that is greater than the volume of erupted magma. We do not understand the factors that control the competition between gas retention and release in magmas, which, in turn, influence how volcanoes erupt. This team will seek answers by studying the potential link between the porosity of volcanic rocks erupted during explosive eruptions and the chemistry of volcanic gas emissions monitored via ground-based measurements at Mt Etna (Italy), the largest volcano in Europe. Around 1 million people live within 30 km of the volcanic vents. This project will support a PhD student and an undergraduate student. Research will be shared in publications and in public lectures, university-based websites, social media, and public mass media. This project aims to bridge the gap between the data and analysis collected by volcano observatories and a burgeoning understanding of magma physics, particularly in the context of the key role of volatile gas species in controlling eruption behavior. The project goal is to correlate the amount of pre- to syn-eruptive porosity in magmas during stages of unrest with gas emissions at active volcanoes. The PI plans to resolve the volume disparity between emitted volcanic gas and erupted magma at Mt Etna (Italy), one of the best monitored and studied volcanoes in the world, by testing two hypotheses: 1) CO2 concentration increase in gas favors porosity increase in mafic magmas, and 2) CO2 / SO2 in gas emissions used to determine mafic magma porosity at depth. The project includes three tasks to test the proposed hypotheses: a) a detailed microstructural and geochemical characterization of volcanic samples from representative eruptions of Mt Etna, b) a time-integrated analysis of magma porosity and volcanic parameters such as CO2 / SO2 ratio, and eruption style, intensity, and magnitude at Mt Etna, and c) modelling of H2O, CO2, and S partitioning between silicate melt and exsolved gas phase in mafic magma during pre-eruptive and syneruptive conditions using existing solubility models. The project includes the collaboration with scientists of the Osservatorio Etneo of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in (Italy) and from the DESY synchrotron facility in Hamburg (Germany).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.