Rheological and Thermodynamic Properties of Subduction Zone Magmas and Lavas - An Integrated Experimental and Observational Study

本项目将研究危地马拉Eschuaguito火山形成块状流的含水英安质至流纹英安质熔岩的流变学和热力学性质。这些有潜力保持移动的几个月到几年，并延伸很长的距离。它们是重大的灾害，最近在日本的aguito和云仙都发生了由流动前沿崩塌造成的块体和火山灰流。 该项目的结果将包括测量在Pakuaguito的火山岩块熔岩的实际温度和含水量，以及它们的粘度和热容量作为化学成分、温度和含水量的函数。这些岩石成分特别有趣，因为安山质岩浆不会形成块状熔岩流，我们将确定是否存在一个“临界熔体结构”，在这个流变学变化发生。研究结果将直接用于改进现有的缓慢移动的块状熔岩流的就位模型，也将用于开发基于构型熵理论的含水（流纹）英安质液体粘度的预测模型，提供改进目前岩浆和火山过程的物理和热模型所需的重要数据。这项工作将与火山观测员密切合作进行在危地马拉的一个项目（INSIVUMEH）中，该项目的目的是使他们更好地了解与块流安置有关的流变学和热量收支，从而有助于提高灾害监测和预测能力。该项目的其他更广泛的影响包括培训研究生粘度和量热技术，并建立了美国第一个将低温粘度测量技术应用于含水硅酸盐液体的实验室。

This project will investigate the rheological and thermodynamic properties of hydrous dacitic to rhyodacitic lavas from Santiaguito volcano in Guatemala, which form block flows. These have the potential to remain mobile for months to years, and to extend great distances. They are significant hazards, and block and ash flows resulting from flow-front collapse have occurred both at Santiaguito and Unzen (Japan) in recent times. Results of this project will include measurements of the actual temperatures and water contents of silicic block-lavas at Santiaguito, and their viscosity and heat capacity as a function of chemical composition, temperature, and water content. These silicic compositions are particularly interesting because andesitic magmas do not form block lava flows, and we will determine whether there is a "critical melt structure" at which this rheological change occurs. The results will be applied directly to refine existing models for the emplacement of slow-moving block lava flows, and will also be used to develop a predictive model of the viscosity of hydrous (rhyo-)dacitic liquids based on configurational entropy theory, providing important data required for improving current physical and thermal models of magmatic and volcanic processes.The work will be carried out in close collaboration with volcano observers in Guatemala (INSIVUMEH), and the aim is to provide them with an improved understanding of rheology and heat budgets related to block flow emplacement, contributing to improved hazard monitoring and prediction capabilities. Other broader impacts of this project include training graduate students in viscometry and calorimetry techniques, and establishing the first laboratory in the USA that will apply low-temperature viscosity measurement techniques to hydrous silicate liquids.