RUI: Collaborative Research: Testing the controls on eruption size and style at intermediate arc volcanoes: Evidence from the Holocene record at Augustine Volcano, USA

该项目由岩石学和地球化学部和已建立的激励竞争性研究计划(EPSCoR)共同资助。阿拉斯加的奥古斯丁火山是美国最频繁的活火山之一，被美国地质调查局认为是非常高的威胁。火山造成的危险取决于喷发的大小和类型，至于是什么控制了像奥古斯丁这样的中弧火山的喷发特征，仍然存在许多问题。例如，大规模和爆炸性的喷发是由地壳浅层大量的岩浆供应驱动的，还是由更快的上升速度驱动的，还是两者兼而有之？从奥古斯丁火山喷发的史前冰盖(命名为Tephra B和Tephra M)可以提供关于喷发行为如何随时间变化的洞察。该项目的目标是调查岩浆管道系统和喷发爆炸性之间的联系。它将针对决定喷发方式的两个主要因素：岩浆成分和岩浆在地壳中上升的速度。这项工作将产生重要的社会效益，特别是与美国的火山灾害有关，并广泛适用于全球其他中弧火山。最后，该项目启动了新的火山观测站--阿拉斯加火山观测站、高露洁大学和米德尔伯里学院之间的学术伙伴关系。这一伙伴关系将加速将基础科学转化为应用和监测，这将在两个本科机构提供积极的以研究为基础的课程。该项目的目标是：1)使用全岩(浮石)、斑晶、玻璃和熔体包裹体地球化学数据，以确定为奥古斯丁地区产生Tephra M和Tephra B单元的喷发提供支持的地下岩浆储集层的数量、几何形状和关系；2)调查岩浆上升速度的指标，如喷发物质中的挥发性浓度、晶体结构和气泡结构；3)通过将TePhas M和B与史前和更新世的历史和更古老的沉积物进行比较，表征火山管道系统随时间的演变；以及4)通过在TePhas M和B，B，Tephas M，B的地层中进行详细采样，调查喷发风格的小尺度变异性有针对性地研究贫微晶石和富含微晶石的样品。这将解决奥古斯丁记录中存在的一些观测偏差，并有助于表征这种偏差在中弧火山的潜在规模和重要性。该项目的数据将对驱动上升和爆炸性的物理和化学过程提供新的限制，并确定岩浆储藏如何随着时间的推移而演变。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。

This project is jointly funded by the Petrology and Geochemistry and the Established Program to Stimulate Competitive Research (EPSCoR) programs. Augustine Volcano in Alaska is one of the most frequently active volcanoes in the US and is considered a very high threat by the U.S. Geological Survey. The hazards posed by a volcano depend on the size and style of an eruption, and many questions remain as to what controls these eruption characteristics at intermediate arc volcanoes like Augustine. For example, are large and explosive eruptions driven by larger volumes of magma supply at shallow depths in the crust, or by faster ascent rates, or both? Prehistoric tephras (named Tephra B and Tephra M) that erupted from Augustine Volcano can provide insight into how eruptive behavior changes through time. This project has as a goal to investigate the links between magma plumbing systems and eruption explosivity. It will target two of the primary factors that determine eruption style: magma composition and the rate at which the magma ascends through the crust. Important societal benefits will emerge from this work, specifically related to volcanic hazards in the US, and that are broadly applicable to other intermediate arc volcanoes globally. Finally, this project initiates new volcano observatory-academic partnerships between the Alaska Volcano Observatory, Colgate University, and Middlebury College. This partnership will accelerate the translation of basic science to applications and monitoring that will provide active research-based curricula at two undergraduate institutions. The goals of this project are to: 1) use whole rock (pumice), phenocryst, glass, and melt inclusion geochemical data to identify the number, geometry, and relationships between the subsurface magmatic reservoirs that fed the eruptions that produced units Tephra M and Tephra B at Augustine, 2) investigate indicators of magmatic ascent rate such as volatile concentrations, crystal textures, and bubble textures within the erupted material, 3) characterize how volcanic plumbing systems evolve through time by comparing tephras B and M to historic and older prehistoric and Pleistocene deposits, and 4) investigate small-scale variability in eruption style through detailed sampling within the stratigraphy of Tephras M and B, with a targeted effort to characterize both microlite-poor and microlite-rich samples. This will resolve some of the observational bias that exists in Augustine’s record, and will help characterize the potential magnitude and importance of this bias at intermediate arc volcanoes. Data from this project will provide new constraints on the physical and chemical processes that drive ascent and explosivity and determine how magma storage reservoirs evolve over time.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.