Tracking ascent rates in an open-vent volcano: Testing textural and geochemical ascent speedometers

跟踪露天火山的上升速率：测试结构和地球化学上升速度计

• 批准号: 2147714
• 负责人: Philipp Ruprecht
• 金额: $ 26.83万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147714&HistoricalAwards=false
• 关键词: Tracking; ascent; rates; open; vent

Volcanic eruptions are sourced from magma chambers in the crust. At what depth magmas are stored and how fast they move to the surface prior to an eruption is of great importance to assess the hazards associated with individual volcanoes. Open-vent volcanoes are particularly hazardous for their lack of unrest signals prior to an eruption. This project specifically focuses the 2018 eruption of the open-vent volcano Mt Veniaminof on the Alaska Peninsula, which poses substantial risk to local communities and aviation through ash emissions. Volatile elements that exsolved on ascent (especially H2O) are the drivers of explosive eruptions. Thus, constraining the volatile element budget in these magmas as well as how fast the volatiles are lost provide important constraints for eruption models and the eruptive behavior of this and similarly behaving volcanoes. A variety of techniques are used to estimate magma ascent and in this study, those techniques will be compared to improve their robustness and test their underlying assumptions. In addition to the scientific benefits, this project will foster collaboration between the USGS/AVO and the academic community, while this collaboration will ensure that existing data sets and samples will continue to be exploited. The Alaska Peninsula is a focus site of geologic research (GeoPRISMS) and our work will complement ongoing geophysical research activities (Amphibious Array). Volatile element data is of importance for geophysics and will inform crustal and upper mantle seismic and magnetotelluric studies. The project supports a collaboration with journalism colleagues to improve science communication and help build a new generation of science-literate journalists. The interplay between magma ascent and textural evolution of basaltic andesites of the 2018 Veniaminof eruption will be studied. Existing estimates for magma ascent rates during the 2018 eruption derived from microlites, will be compared against independently determined ascent rates from melt embayments hosted in olivine. To interpret the embayment and textural record, we will also collect melt inclusion volatile data to constrain the volatile element budget in the crustal storage region prior to ascent. The work includes a series of analytical techniques (Raman, x-ray computed tomography, SIMS, FTIR, EPMA, LA-ICPMS) to fully characterize and correct the volatile budget. Fundamental assumptions related to embayment studies will be tested: 1) the uniformity of ascent rates among embayments, 2) changes over the course of an eruptive episode, 3) the effect of embayment necking. The project will be complemented with the development of a thermodynamic model that captures the driving forces for crystallization and dissolution through the calculation of chemical affinities along any preferred P-T-X-time path.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.

火山喷发源自地壳中的岩浆房。岩浆储存的深度以及它们在喷发前移动到地表的速度对于评估与个别火山相关的危害非常重要。露天火山特别危险，因为它们在喷发前缺乏动荡信号。该项目特别关注 2018 年阿拉斯加半岛韦尼亚米诺夫露天火山的喷发，该火山喷发的火山灰给当地社区和航空业带来了巨大风险。上升时溶解的挥发性元素（尤其是水）是爆炸性喷发的驱动因素。因此，限制这些岩浆中的挥发性元素预算以及挥发物流失的速度为喷发模型以及该火山和类似火山的喷发行为提供了重要的约束。有多种技术用于估计岩浆上升，在本研究中，将对这些技术进行比较，以提高其稳健性并测试其基本假设。除了科学效益外，该项目还将促进 USGS/AVO 和学术界之间的合作，而这种合作将确保现有的数据集和样本将继续得到利用。阿拉斯加半岛是地质研究（GeoPRISMS）的重点地点，我们的工作将补充正在进行的地球物理研究活动（两栖阵列）。挥发性元素数据对于地球物理学非常重要，将为地壳和上地幔地震和大地电磁研究提供信息。该项目支持与新闻界同事合作，以改善科学传播并帮助培养新一代具有科学素养的记者。将研究 2018 年韦尼亚米诺夫喷发的岩浆上升与玄武安山岩结构演化之间的相互作用。对 2018 年微晶石喷发期间岩浆上升速率的现有估计将与橄榄石熔体海湾独立确定的上升速率进行比较。为了解释海湾和结构记录，我们还将收集熔体包裹体挥发性数据，以限制上升前地壳储存区域的挥发性元素预算。这项工作包括一系列分析技术（拉曼、X 射线计算机断层扫描、SIMS、FTIR、EPMA、LA-ICPMS），以充分表征和纠正不稳定的预算。将测试与海湾研究相关的基本假设：1）海湾之间上升率的一致性，2）喷发事件过程中的变化，3）海湾颈缩的影响。该项目将通过热力学模型的开发得到补充，该模型通过沿任何首选 P-T-X-时间路径计算化学亲和力来捕获结晶和溶解的驱动力。该奖项反映了 NSF 的法定使命，并通过评估被认为值得支持利用基金会的智力优势和更广泛的影响审查标准。