CAREER: Characterizing the Physical/Chemical Evidence of Volcanic Lightning

火山喷发和闪电是最令人印象深刻和最具破坏性的两种自然现象，但导致这些事件发生的基本过程仍有许多未知之处。一个新兴的研究领域正在寻求确定火山爆发和闪电之间的复杂关系，特别是：闪电排放对火山灰的结构和化学性质的影响，以及由此产生的地质记录中火山闪电发生的特征。除了云对地闪电形成闪锌矿外，由于闪电放电产生的高热，火山灰颗粒在物理上转化为玻璃球体，从而在大气中形成了闪电诱导的火山球体(LIVS)。该项目将通过以下方式确定火山闪电的物理化学证据：1)在天然火山灰沉积中识别LIVS，并使用现有方法分析其质地/化学性质；2)对已知组成和粒度的人造火山灰样本进行一系列触发闪电实验，以利用各种分析方法表征火山闪电对样本的物理/化学影响；3)建立一个由研究生、本科生和高中生组成的研究小组，进行实验和分析样本；以及4)开发小学课程，在当地学校教授自然灾害，以便让学生参与地球科学。该项目涉及的基本问题，以及涉及所有年龄段的学习者的综合教育部分，可能会产生潜在的变革性概念，如地球科学、大气科学和灾害评估。从样本上获得的纹理和地球化学数据将提供地质记录中火山闪电的证据，使研究人员能够在喷发期间识别这些事件，这些事件发生在人类记录之前或之前。结果还将揭示闪电在改变当地环境的化学特征方面所起的作用。此外，在已知成分的人造火山灰样本上进行的触发闪电实验，将允许对电闪石的形成进行视频记录。通过科学和社区介绍，该项目将进一步激发人们对火山学、大气动力学以及这些自然现象之间复杂相互作用的兴趣，不仅在科学界，而且在学校和公众中。该项目的主要目标是描述火山闪电在特弗拉矿床中发生的物理/化学证据，这将有助于了解地质记录中火山闪电的频率，有助于增进对火山-大气相互作用的科学知识，这是一种新兴的科学研究方向。将对阿拉斯加多次火山喷发的火山灰沉积进行分析，因为在这些爆炸事件中记录了火山闪电，样本由阿拉斯加火山天文台提供。触发闪电实验将在国际闪电研究和测试中心(ICLRT)对已知成分和粒度的人造火山灰样本(伪火山灰样本)进行。已建立的分析方法包括：1)对天然火山灰样品中存在的闪电诱导的火山球(LIVS)进行扫描电子显微镜(SEM)、透射式电子显微镜(TEM)和电子自旋共振(ESR)检查，以确定其结构和化学特征；2)对天然火山灰和实验前的假火山灰进行ESR、穆斯堡尔和滴定分析；以及3)对触发闪电实验中产生的LIVS和电闪石进行扫描电子显微镜(SEM)、透射电子显微镜(TEM)、电子自旋共振(ESR)、穆斯堡尔谱(穆斯堡尔)和滴定分析。由研究生、本科生和高中生组成的研究团队将进行实验并分析样本。当在触发闪电实验之前和之后对假火山灰样品进行各种分析时，可以直接确定闪电放电对暴露材料的形态转变、一般化学和氧化/铁价态的影响。天然灰样将允许对沉积物中存在的正常(即未改性)灰分和任何LIV进行化学比较。结果公布后，触发闪电实验的视频将在阿拉巴马大学S Tephra实验室的网站上YouTube上展示，并在阿拉巴马州自然历史博物馆展出，以及触发闪电实验中产生的天然电闪石和电闪石的样本。该项目涉及的基本问题，以及涉及所有年龄段的学习者的综合教育部分，可能会产生潜在的变革性概念，如地球科学、大气科学和灾害评估。从样本上获得的纹理和地球化学数据将提供地质记录中火山闪电的证据，使研究人员能够在喷发期间识别这些事件，这些事件发生在人类记录之前或之前。结果还将揭示闪电在改变当地环境的化学特征方面所起的作用。此外，在已知成分的人造火山灰样本上进行的触发闪电实验，将允许对电闪石的形成进行视频记录。通过科学和社区介绍，该项目将进一步培养人们对火山学、大气动力学以及这些自然现象之间复杂的相互作用的兴趣，不仅在科学界，而且在学校和普通公众中。

Volcanic eruptions and lightning strikes are two of the most impressive and destructive natural phenomena, but much is still unknown about the fundamental processes that allow these events to occur. An emerging new line of research is seeking to determine the complex relationship between explosive volcanism and lightning, specifically: The effect of lightning discharge on the textural and chemical properties of volcanic ash and the resulting signature of volcanic lightning occurrence in the geologic record. In addition to the formation of fulgurites as a result of cloud-to-ground lightning strikes, lightning-induced volcanic spherules (LIVS) form in the atmosphere from the physical transformation of volcanic ash particles into spheres of glass due to the high heat generated during lightning discharge. This project will characterize the physiochemical evidence of volcanic lightning by: 1) identifying LIVS in natural ash fall deposits and analyzing their textural/chemical properties using established methods; 2) performing a series of triggered lightning experiments on manufactured ash samples of known composition and grain size to characterize the physical/chemical effects of volcanic lightning on the samples using various analytical methods; 3) establishing a research team of graduate, undergraduate, and high school students to perform the experiments and analyze the samples; and 4) developing grade school curricula for teaching natural hazards in local schools in order to engage students in the Earth sciences. Fundamental questions addressed by this project, and the integral educational component that involves learners of all ages, may result in potentially transformative concepts the geosciences, atmospheric sciences, and hazard assessment. Textural and geochemical data acquired on the samples will provide evidence for volcanic lightning in the geologic record, allowing researchers to identify these events during eruptions that preceded or eluded human documentation. Results will also reveal the role that lightning plays in altering the chemical characteristics of the local environment. Additionally, the triggered lightning experiments, conducted on manufactured ash samples of known composition, will allow video documentation of fulgurite formation. Through scientific and community presentations, this project will build further interest in volcanology, atmospheric dynamics, and the complex interplay between these natural phenomena, not only in the scientific community, but also in schools and amongst the general public.The primary goal of this project is to characterize the physical/chemical evidence of volcanic lightning occurrence in tephra deposits, which will aid in understanding the frequency of volcanic lightning in the geologic record, contributing to advancing scientific knowledge of volcano-atmosphere interactions, which is an emerging new line of scientific research. Ash fall deposits from numerous volcanic eruptions in Alaska will be analyzed, as volcanic lightning was documented during these explosive events and samples were provided by the Alaska Volcano Observatory. Triggered lightning experiments will be conducted at the International Center for Lightning Research and Testing (ICLRT) on manufactured ash samples (pseudo-ash samples) of known composition and grain size. The established analytical methods that will be utilized for this project include: 1) Scanning electron microscope (SEM), transmission electron microscope (TEM), and electron spin resonance (ESR) examination of lightning-induced volcanic spherules (LIVS) present in natural ash samples to determine their textural and chemical characteristics; 2) ESR, Mossbauer, and titration analyses of both natural, unmodified ash and pre-experimental pseudo-ash; and 3) SEM, TEM, ESR, Mossbauer, and titration analyses of LIVS and fulgurites produced in the triggered lightning experiments. A research team of graduate, undergraduate, and high school students will perform the experiments and analyze the samples. The various analyses, when conducted on the pseudo-ash samples prior to and following the triggered lightning experiments, will allow a direct means to determine the effect of lightning discharge on the morphological transformation, general chemistry, and oxidation/Fe valence state of exposed materials. The natural ash samples will allow a chemical comparison between normal (i.e., unmodified) ash and any LIVS present in the deposits. Following publication of results, the videos of triggered lightning experiments will be displayed on the University of Alabama?s Tephra Lab website, on YouTube, and showcased in the Alabama Museum of Natural History, along with samples of both natural fulgurites and fulgurites created in the triggered lightning experiments. Fundamental questions addressed by this project, and the integral educational component that involves learners of all ages, may result in potentially transformative concepts the geosciences, atmospheric sciences, and hazard assessment. Textural and geochemical data acquired on the samples will provide evidence for volcanic lightning in the geologic record, allowing researchers to identify these events during eruptions that preceded or eluded human documentation. Results will also reveal the role that lightning plays in altering the chemical characteristics of the local environment. Additionally, the triggered lightning experiments, conducted on manufactured ash samples of known composition, will allow video documentation of fulgurite formation. Through scientific and community presentations, this project will build further interest in volcanology, atmospheric dynamics, and the complex interplay between these natural phenomena, not only in the scientific community, but also in schools and amongst the general public.