CAREER: Characterizing the Physical/Chemical Evidence of Volcanic Lightning

职业：描述火山闪电的物理/化学证据

• 批准号: 1553878
• 负责人: Kimberly Genareau
• 金额: $ 43.39万
• 依托单位: University of Alabama Tuscaloosa
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-01 至 2023-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1553878&HistoricalAwards=false
• 关键词: CAREER; Characterizing; Physical; Chemical; Evidence

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.

火山爆发和雷击是两种最令人印象深刻和最具破坏性的自然现象，但人们对这些事件发生的基本过程仍然知之甚少。一项新兴的研究正在寻求确定爆发性火山活动与闪电之间的复杂关系，特别是：闪电放电对火山灰的结构和化学性质的影响以及地质记录中火山闪电发生的特征。除了因云对地雷击而形成雷电岩外，由于闪电放电过程中产生的高热，火山灰颗粒物理转变为玻璃球，从而在大气中形成雷电火山球体（LIVS）。 该项目将通过以下方式描述火山闪电的物理化学证据：1）识别天然火山灰沉积物中的 LIVS，并使用既定方法分析其结构/化学特性； 2) 对已知成分和颗粒尺寸的人造灰样品进行一系列触发闪电实验，以使用各种分析方法表征火山闪电对样品的物理/化学效应； 3）建立一个由研究生、本科生和高中生组成的研究团队，进行实验和样品分析； 4) 开发当地学校教授自然灾害的小学课程，以吸引学生学习地球科学。该项目解决的基本问题以及涉及所有年龄段学习者的整体教育部分可能会产生地球科学、大气科学和灾害评估等潜在变革性概念。从样本中获取的纹理和地球化学数据将为地质记录中的火山闪电提供证据，使研究人员能够识别这些在人类记录之前或无法记录的火山爆发期间发生的事件。 结果还将揭示闪电在改变当地环境化学特征方面所发挥的作用。 此外，在已知成分的人造灰样品上进行的触发闪电实验将允许对电闪岩形成进行视频记录。 通过科 火山与大气的相互作用，这是一个新兴的科学研究领域。将分析阿拉斯加多次火山喷发产生的火山灰沉积物，因为在这些爆炸事件期间记录了火山闪电，并且阿拉斯加火山观测站提供了样本。 触发闪电实验将在国际闪电研究和测试中心 (ICLRT) 对已知成分和颗粒尺寸的人造灰样品（伪灰样品）进行。该项目将使用的既定分析方法包括： 1）扫描电子显微镜（SEM）、透射电子显微镜（TEM）和电子自旋共振（ESR）检查天然灰样品中存在的雷电诱发火山小球（LIVS），以确定其结构和化学特征； 2) 天然、未改性灰分和实验前假灰分的 ESR、穆斯堡尔和滴定分析； 3) 对触发闪电实验中产生的 LIVS 和电闪石进行 SEM、TEM、ESR、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。在触发闪电实验之前和之后对伪灰样品进行各种分析，将能够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。 天然灰分样品可对正常（即未改性）灰分与沉积物中存在的任何 LIVS 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 Tephra 实验室网站、YouTube 上展示，并在阿拉巴马自然历史博物馆展出，同时还会展示天然雷电岩和触发闪电实验中产生的雷电岩样本。 该项目解决的基本问题以及涉及所有年龄段学习者的整体教育部分可能会产生地球科学、大气科学和灾害评估等潜在变革性概念。从样本中获取的纹理和地球化学数据将为地质记录中的火山闪电提供证据，使研究人员能够识别这些在人类记录之前或无法记录的火山爆发期间发生的事件。 结果还将揭示闪电在改变当地环境化学特征方面所发挥的作用。 此外，在已知成分的人造灰样品上进行的触发闪电实验将允许对电闪岩形成进行视频记录。 通过科学和社区演示，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。