CAREER: Reactivation controls, timescales, and styles at quiescent hotspot volcanoes: Insights from the Canary Islands

这一职业奖旨在量化静止火山重新激活再次喷发的过程的性质和时间尺度。理解这一复兴过程仍然是现代火山科学的一个具有挑战性但重要的目标。前兆活动持续时间(即喷发启动)与休止期和岩浆成分等其他变量之间的一般关系有望改善喷发预测和对火山生命周期的了解，但需要在“受控”个案研究中进一步检验。加那利群岛拥有四个不同岛屿上13次历史性喷发的数据，这些数据限制了地壳结构、岩浆系统配置、岩浆成分、休止期和喷发方式，是测试来自地球深处的静止热点火山行为的理想自然实验室。初步数据表明：(1)加那利岛火山的重新激活受控于新的深源岩浆流入上地幔岩浆系统；(2)从深源岩浆流入到喷发之间的时间间隔通常在几个月左右。为了验证这些假设，这项研究将通过对晶体图像的分析和课堂研究的整合，记录所有13次喷发中大量橄榄石和单斜辉石晶体的成分分带风格。此外，还将对一批有代表性的晶体和捕获在其中的火山玻璃小包裹体进行定量微观分析。这些数据将被用来确定导致火山重新活动的岩浆过程，并计算所有喷发的喷发准备。该项目的设计将进一步测试火山喷发是否取决于地壳结构、休止期和岩浆成分，以及是否与喷发方式有关，这将提高我们对这些火山及其相关灾害的内部工作原理的了解。这一职业项目的教育部分以实施以课程为基础的本科生研究经验为中心，这将使学生参与研究设计、样本准备、数据收集以及结果的解释和传播，从而直接为工作的科学目标提供信息。首席调查员、研究生和本科生之间的分级和近乎同行的指导计划将促进学生的成功，并将得到既定导师培训计划的支持。现场和在线外联活动将与加那利群岛的一个火山解释中心协调。最后，将制作视频教程并公开提供，以便于其他研究人员、教育工作者和学生使用我们的方法。该项目的自然实验利用历史上加那利岛喷发的现有数据及其产品的系统岩石学分析，以分离导致静止热点火山重新激活的变量--并控制其持续时间和风格。许多晶体的背向散射电子图像的灰度分析将与对选定晶体的高精度电子探针分析相结合。此外，还将对这些相同晶体中熔体包裹体的挥发性和微量元素浓度进行拉曼、离子探针和LA-ICPMS测量。扩散计时法将用于量化加那利群岛所有13个历史性喷发的喷发准备情况，这将为该群岛的危险评估和未来喷发预测工作提供重要数据。这种方法反过来将允许测试假设的全球关系之间的喷发准备阶段，休止期，岩浆成分，以及喷发方式在单个热点地区的个别火山。这项工作将促进对橄榄石和单斜辉石如何记录岩浆过程及其时间尺度的理解，并将揭示对玄武岩岩浆结晶货物的新见解。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 CAREER award seeks to quantify the nature and timescales of processes by which quiescent volcanoes reactivate to erupt again. Understanding this rejuvenation process remains a challenging, but important goal of modern volcano science. General relationships between the duration of precursory activity (that is, eruption run-up) and other variables, such as repose period and magma composition, are promising for improved eruption forecasting and understanding of the life cycles of volcanoes, but need further testing at “controlled” case studies. With available data on 13 historic eruptions across four different islands providing constraints on crustal structure, magmatic system configuration, magma composition, repose period, and eruption style, the Canary Islands represent an ideal natural laboratory to test ideas on the behavior of quiescent hotspot volcanoes fed from deep within Earth. Preliminary data suggest that (1) reactivation of Canary Island volcanoes is controlled by new influx of deep-sourced magma into the upper mantle magmatic system and that (2) the time lapse between this deep recharge and eruption is typically on the order of a few months. In order to test these hypotheses, this study will document the style of compositional zoning of a large number of olivine and clinopyroxene crystals across all 13 eruptions, through analysis of crystal images and integration of research in the classroom. This will be complemented by quantitative micro-analysis on a subset of representative crystals and small inclusions of volcanic glass trapped within them. These data will be utilized to identify magmatic processes leading to volcano reactivation and to calculate eruption run-up for all eruptions. The design of this project will further allow testing whether eruption run-up is dependent upon crustal structure, repose period, and magma composition and whether it has an incidence on eruption style, which will improve our understanding of the inner workings of these volcanoes and associated hazards. The educational component of this CAREER project centers on the implementation of a course-based undergraduate research experience, which will involve students in research design, sample preparation, data collection, and interpretation and dissemination of results and, whereby, will directly inform the scientific goals of the work. A tiered and near-peer mentoring plan between the principal investigator, graduate students, and undergraduate students will foster student success and will be supported by an established mentor training program. On-site and online outreach activities will be coordinated with a volcano interpretive center in the Canary Islands. Finally, video tutorials will be produced and made openly available to facilitate the use of our approach by other researchers, educators, and students. The natural experiment of this project exploits available data on historic Canary Island eruptions and systematic petrologic analyses of their products to isolate variables that cause reactivation — and control its duration and style — at quiescent hotspot volcanoes. Grayscale analysis of backscatter electron images of numerous crystals will be combined with high-precision electron probe analysis on selected crystals. In addition, Raman, ion microprobe and LA-ICP-MS measurements of volatile and trace element concentrations of melt inclusions within these same crystals will be performed. Diffusion chronometry will be used to quantify eruption run-up for all 13 historic eruptions in the Canary Islands, which will provide important data for hazard assessment and future eruption forecasting efforts in the archipelago. This approach will in turn allow testing postulated global relationships between eruption run-up, repose period, magma composition, and eruption style at individual volcanoes across a single hotspot. The work will advance the understanding of how olivine and clinopyroxene record magmatic processes and their timescales and will reveal new insights into the crystal cargo of basaltic magmas.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.