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

到目前为止，熔岩流是最常见的火山活动形式。由于全世界有超过10亿人生活在活火山附近，准确预测熔岩流动危险是当务之急。虽然熔岩流很少致人死亡，但它们经常会摧毁房屋和基础设施，有时会在一次事件中造成数百万美元的损失。为了减轻这种危险，该项目试图了解熔岩流动是如何推进的。熔岩流的推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。该项目将通过实验室实验再现真实的熔岩流动冷却路径，并测量熔岩如何在整个过程中变形和移动变化。此外，该团队将开发一个关于熔岩流运动的学习单元，专门为不断增长的家庭学校社区的独特需求量身定做，从而推进NSF促进所有公民获得STEM学习和培训的目标。熔岩流中的每一量都受到独特的冷却历史的影响，这导致任何给定的熔岩流在空间和时间上都会产生不同的晶体组合和纹理，并最终产生流变学。最先进的流变学实验采用等温条件或恒定冷却速度。然而，天然熔岩流经历了更微妙的冷却历史。这一提议的首要目标是通过实验确定玄武岩熔岩的结晶和流变性在经历真实的冷却曲线时是如何演变的。该产品将是一张详细的、基于物理的玄武岩熔岩流的流变图。由于流变学在控制熔岩流推进速度和动态方面发挥了关键作用，本成果将为社区提供一个关键工具，以提高我们预测熔岩流侵位的能力，并潜在地减轻对基础设施的破坏。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.