Collaborative Research: From the Slab to the Surface: Origin, Storage, Ascent and Eruption of Volatile-Bearing Magmas

在任何一天，全世界大约有 15-30 座火山正在喷发或显示出强烈的不稳定迹象（例如异常高的地震活动率、地面变形或气体排放）。火山活动，包括高空火山喷发或大量气体的排放，对美国和全世界的人民和财产构成重大危害。在阿拉斯加尤其如此，每天有超过 10,000 名乘客沿着北美/亚洲航线飞越 35 座历史上的活火山。尽管近几十年来，人们在了解地壳上部发生的直接导致火山活动和相关动乱的物理过程方面取得了重大进展，但对这些浅层地壳过程如何与最终导致弧火山活动的大规模地壳构造和深部地幔熔化联系起来并受其控制，仍缺乏了解。具体来说，尽管众所周知，岩浆中溶解的水和其他挥发物的量在岩浆的产生、上升和喷发中起着关键作用，但尚不清楚为什么一些弧火山会比其他火山喷发“更湿润”的岩浆。因此，确定对岩浆挥发物含量的大规模控制对于准确预测火山喷发的频率、体积和爆炸性至关重要。在这里，我们提出对阿留申火山弧的乌尼马克-克利夫兰走廊进行综合地球化学-地球物理研究，该走廊包括过去 25 年中喷发的六座火山，岩浆水含量变化很大。这个相对较小的走廊还表现出一系列深部和上地壳地震活动、明显的岩浆储存深度以及俯冲板块的深度。我们的目标是将两个通常互不相关的宏观问题联系起来：1）岩浆和挥发物的深层起源，2）地壳岩浆库的形成和喷发，我们建议通过确定整个走廊的地壳岩浆库深度和喷发前挥发物含量来实现这一目标。综合研究内容包括火山地震事件分析和岩浆挥发分分析。现有的地震数据目录包含约 14,000 个事件，并且一些火山喷发产物的样本已经在手。走廊中存在两座活跃喷发的火山，进一步促进了在喷发期间同时收集地震、气体（与美国地质勘探局阿拉斯加火山观测站合作）和火山灰样本，这些样本反映了岩浆系统的活跃演化。

On any given day, approximately 15-30 volcanoes worldwide are either in eruption or show strong signs of unrest (e.g., anomalously high rates of seismic activity, ground deformation, or gas emissions). Volcanic activity, including high-altitude eruptions of ash or emission of large volumes of gas, poses a significant hazard to people and property in the United States and worldwide. This is particularly true in Alaska, with over 10,000 passengers a day flying over 35 historically active volcanoes on North America/Asia flight routes. Although significant progress has been made in recent decades in understanding the physical processes occurring in the upper portions of the Earth's crust that lead directly to volcanic activity and associated unrest, there is a fundamental lack of understanding of how these shallow crustal processes link to and are controlled by the large-scale crustal tectonics and deep mantle melting that are ultimately responsible for arc volcanism. Specifically, although it is well understood that the amount of water and other volatiles dissolved in a magma plays a key role in its generation, ascent, and eruption, it is unclear why some arc volcanoes erupt 'wetter' magmas than others. Identifying large scale controls on magma volatile contents is thus critical for accurate forecasting of the frequency, volume, and explosivity of volcanic eruptions. Here, we propose an integrated geochemical-geophysical study of the Unimak-Cleveland corridor of the Aleutian volcanic arc, which encompasses six volcanoes that have erupted in the past 25 years with a wide range of magmatic water contents. This relatively small corridor also exhibits a range of deep and upper-crustal seismicity, apparent magma storage depths, and depths to the subducting tectonic plate. Our goal is to link two normally disconnected big-picture problems: 1) the deep origin of magmas and volatiles, and 2) the formation and eruption of crustal magma reservoirs, which we propose to do by establishing the depth(s) of crustal magma reservoirs and pre-eruptive volatile contents throughout the corridor. The integrated study components include analysis of volcano- seismic events and magmatic volatile analysis. Existing seismic data catalogs contain ~ 14,000 events, and some samples of volcanic eruption products are already in hand. The existence of two actively erupting volcanoes in the corridor further motivates collection of simultaneous seismic, gas (in collaboration with the USGS Alaska Volcano Observatory) and tephra samples during eruption, that reflect active evolution of the magmatic system.