Emission Spectroscopy of Silicic Lavas: Implications for Dome Processes and Hazards

由于过度陡峭和/或流动前沿坍塌造成的火山熔岩圆顶的爆炸性减压可能产生中等至大的火山碎屑流。 在过去十年中，此类事件在蒙特塞拉特岛和日本云仙岛的苏弗里埃山等火山造成了大量人员伤亡和财产损失。 对圆顶表面发射的热红外（TIR）能量的详细检查可以提供熔岩成分和微米级表面纹理的定量数据。 例如，玻璃质熔岩中表面小泡的百分比倾向于使发射率吸收带的光谱对比度与其表面丰度成线性比例地减弱或降低。 这个派生的参数提供了重要的见解圆顶安置/演变，并与温度和表面变形，有直接的影响圆顶的危险状态。 发射光谱法与傅里叶变换红外显微镜法的不同之处在于，它适用于捕获关于整个岩石样品、宏观表面纹理和遥感应用的信息。 然而，为了提供可靠地解释这些数据所需的严格和定量分析，提出了两个目标：（1）对各种成分的玻璃质熔岩进行详细的实验室分析，这将导致红外光谱特征与化学成分和结构形态之间的定量相关性;和（2）将这项研究扩大到对蒙特塞拉特苏弗里埃山火山穹丘的实地研究和对俄罗斯Bezimianny火山穹丘的遥感研究。 这种应用程序的活动圆顶将有关的熔岩的化学变化的纹理信息来自实验室的研究。 它还在实验室分析/比例与空间分析/比例之间架起了一座重要的桥梁。 这项研究的智力价值是对天然矿物和岩石玻璃的热红外发射进行更完整的分析和理论分析。 这反过来又将使人们准确地了解与主动拱顶安放过程和监测之间的联系。这一项目的更广泛影响包括对一名研究生、一名来自代表人数不足的地理群体的博士后研究员和几名本科生进行实验室、计算机和实地培训。 此外，这些结果将促进对从玻璃/富囊泡样品中获得的发射光谱的科学理解。 这一知识有可能导致开发一种新的空间和地面科学工具，可用于监测活动穹丘的形成过程及其随后的潜在危害。

EAR-0309631Ramsey Explosive decompression of silicic lava domes due to over-steepening and/or flow front collapse can produce moderate to large pyroclastic flows. Such events have resulted in numerous casualties and property damage in the past decade at volcanoes such as Soufriere Hills, Montserrat and Unzen, Japan. The detailed examination of thermal infrared (TIR)-emitted energy from a dome's surface can provide quantitative data on the composition and micrometer-scale surface texture of the lava. For example, the percentage of surface vesicles in glassy lavas tends to mute or reduce the spectral contrast of the emissivity absorption bands in linear proportion to their surface abundance. This derived parameter has provided important insights into dome emplacement/evolution, and where coupled with temperature and surface deformation, has direct implications for the hazard state of the dome. Emission spectroscopy differs from Fourier-transform infrared (FTIR) microscopy in its applicability to capture information on whole rock samples, macroscopic surface textures and remote sensing applications. However, in order to provide the rigorous and quantitative analysis needed to confidently interpret these data, two objectives are proposed: (1) to perform a detailed laboratory-based analysis of glassy lavas of various compositions, which will result in a quantitative correlation between infrared spectral features and the chemical composition and textural morphology; and (2) extend that research to both a field-based study of the Soufriere Hills volcanic dome, Montserrat and a remote sensing-based study of the Bezymianny volcanic dome, Russia. This application to active domes will relate the chemical variation in the lavas to textural information derived from the laboratory studies. It also provides a critical bridge between the laboratory analysis/scale and those derived from space. The intellectual merit of the research is a more complete analytical and theoretical analysis of the thermal infrared emission of naturally occurring mineral and rock glasses. This in turn will provide an accurate understanding of the linkages to active dome emplacement processes and monitoring. The broader implications of this project include laboratory, computer and field training of one graduate student, one post-doctoral researcher from an under-represented geographical group, and several undergraduate students. In addition, the results will advance the scientific understanding of emission spectroscopy acquired from glass/vesicle-rich samples. That knowledge has the potential to lead to the development of a new space and ground-based scientific tool, which can be used to monitor the processes of active dome formation and its subsequent hazard potential.