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

该职业奖旨在量化静止火山再次喷发过程的性质和时间尺度。了解这一再生过程仍然是现代火山科学的一个具有挑战性但又重要的目标。前兆活动持续时间（即喷发预备期）与其他变量（例如休止期和岩浆成分）之间的一般关系有望改善喷发预测和对火山生命周期的理解，但需要在“受控”案例研究中进一步测试。加那利群岛拥有四个不同岛屿上 13 次历史喷发的可用数据，这些数据提供了对地壳结构、岩浆系统配置、岩浆成分、休止期和喷发风格的限制，加那利群岛是一个理想的自然实验室，可以测试来自地球深处的静止热点火山的行为。初步数据表明，（1）加那利群岛火山的重新激活受到新的深源岩浆流入上地幔岩浆系统的控制，（2）这种深层补给和喷发之间的时间间隔通常约为几个月。为了检验这些假设，本研究将通过晶体图像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区类型。这将通过对代表性晶体子集和其中捕获的火山玻璃小夹杂物进行定量微观分析来补充。这些数据将用于识别导致火山重新激活的岩浆过程，并计算所有喷发的喷发预备期。该项目的设计将进一步测试喷发预备期是否取决于地壳结构、休止期和岩浆成分，以及是否与喷发类型有关，这将提高我们对这些火山内部运作和相关危害的了解。该职业项目的教育部分以实施基于课程的本科研究经验为中心，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，从而直接告知工作的科学目标。首席研究员、研究生和本科生之间的分层和近同行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。现场和在线外展活动将与加那利群岛的火山解说中心协调。最后，将制作并公开提供视频教程，以方便其他研究人员、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了加那利群岛历史喷发的现有数据及其产物的系统岩石学分析，以隔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类型。对众多晶体的反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内的熔体夹杂物的挥发性和痕量元素浓度进行拉曼、离子微探针和 LA-ICP-MS 测量。扩散计时法将用于量化加那利群岛所有 13 次历史喷发的喷发准备阶段，这将为该群岛的灾害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单个热点地区各个火山的喷发准备期、休止期、岩浆成分和喷发风格之间假设的全局关系。这项工作将增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晶体货物的新见解。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值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.