VISCOSITY PATHS: Assessing the Effect of Realistic Cooling Rates on the Evolution of Lava Flow Rheology

熔岩流是迄今为止最常见的火山活动形式。由于全球有超过10亿人居住在活火山附近，因此准确预测熔岩流灾害势在必行。虽然熔岩流很少致人死亡，但它们经常摧毁房屋和基础设施，有时在一次事件中造成数百万美元的损失。为了减轻这种危险，这个项目试图了解熔岩流是如何前进的。熔岩流的前进在很大程度上取决于它们如何从喷发时的主要液体转变为完全固体，因为它们从喷口流出并冷却下来。该项目将通过实验室实验重现真实的熔岩流冷却路径，并测量熔岩在整个过程中变形和移动变化的能力。此外，该团队将开发一个专门针对不断增长的家庭教育社区的独特需求的熔岩流运动的学习单元，从而推进NSF促进所有公民获得STEM学习和培训的目标。熔岩流中的每一个量子都有一个独特的冷却历史，这导致了不同的晶体组合和纹理，以及最终的流变，对于任何给定的熔岩流在空间和时间上都是如此。最先进的流变学实验要么假设等温条件，要么假设恒定的冷却速率。然而，自然熔岩流经历了更微妙的冷却历史。本提案的首要目标是通过实验确定玄武岩熔岩的结晶和流变学如何在实际冷却曲线下演变。该产品将是一个详细的，基于物理流变演化图的通道化玄武岩熔岩流。由于流变学在控制熔岩流推进速度和动力学方面发挥着关键作用，该成果将为社区提供一个关键工具，以提高我们预测熔岩流就位的能力，并潜在地减轻对基础设施的损害。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Lava flows are by far the most common form of volcanic activity. With more than 1 billion people worldwide living near an active volcano, it is imperative to accurately forecast lava flow hazard. While lava flows rarely kill people, they routinely destroy houses and infrastructure, sometimes causing millions of dollars of damage in a single event. In order to mitigate this hazard, this project seeks to understand how lava flows advance. The advance of lava flows largely depends on how they transition from being mainly liquid at eruption to fully solid as they flow away from the vent and cool down. This project will reproduce realistic lava flow cooling paths through laboratory experiments, and measure how lava ability to deform and move changes throughout the process. Further, the team will develop a learning unit on lava flow motion specifically tailored to the unique needs of the ever-growing homeschooling community, thus advancing NSF’s goal of promoting access to STEM learning and training for all citizens. Each quantum of lava within a flow is subject to a unique cooling history, which results in varying crystal assemblages and textures, and ultimately rheology, for any given lava flow in both space and time. State-of-the-art rheological experiments assume either isothermal conditions or constant cooling rates. However, natural lava flows experience much more nuanced cooling histories. The overarching goal of this proposal is to experimentally determine how the crystallization and thus rheology of basaltic lava evolve when subjected to realistic cooling curves. The product will be a detailed, physics-based rheological evolution map of a channelized basaltic lava flow. Because of the key role played by rheology in controlling lava flow advance speed and dynamics, this deliverable will provide the community with a key tool to improve our ability to forecast lava flow emplacement, and to potentially mitigate damage to infrastructure.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.