Collaborative Research: Closing the Loop on Lava Flow Models: Linking Thermal and Mechanical Controls on Flow Emplacement Dynamics Using Novel Field and Experimental Techniques

合作研究：熔岩流模型的闭环：利用新的领域和实验技术将热和机械控制联系起来对流动安置动力学

• 批准号: 0739153
• 负责人: Samuel Soule
• 金额: $ 11.69万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-15 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0739153&HistoricalAwards=false
• 关键词: Collaborative; Research; Closing; Loop; Lava

The considerable hazard to property and infrastructure posed by effusive lava flows in volcanically active areas motivates this project to understand the physics of lava flow emplacement and improve our ability to predict their behavior. A fundamental control on the dynamics of lava flows arises from their rheology, which changes from fluid-like on eruption to solid-like during emplacement. This complex behavior has been investigated by accounting for either the mechanical or thermal evolution of a flow, but rarely have these approaches been coupled. This proposed work aims to link these two parallel approaches by developing new methods for quantifying lava flow morphology, which records the coupled thermal and mechanical evolution of the lava. It is proposed to use airborne- and ground-based laser mapping techniques to construct high-resolution (from 1 cm to ~1m) topographic maps with which we can resolve such features as individual clasts on lava surfaces to lava channels/levees and flow margins. Morphology observations will be coupled with laboratory measurements of the physical properties of the lava and physical experiments using analog materials that simulate lava flow behavior. The integrated experimental and observational will be used to test and refine predictive models of flow emplacement. Fieldwork will be conducted at two locations: Mauna Loa Volcano and the Oregon Cascades. These sites provide a range of initial lava compositions and eruption styles, making the results widely applicable to volcanically active areas globally.During emplacement, lava flows develop viscous and visco-elastic rheologies that, coupled with a solidifying crust, produce complex responses to deformation. For this reason, models of flow emplacement must consider both the mechanical and the thermal history of a flow. Mechanical models include gravitational spreading of viscous and Bingham yield strength fluids. Thermal models of have focused on basaltic lava channels, specifically on the reduction of flow cooling rates with increasing coverage of a solid surface, while the role of solidification on flow dynamics has been examined by determining tensional failure criteria of that solid crust. Until recently, models that link thermal and dynamical regimes have been limited to low Reynolds number (low flux) flow in radial spreading regimes. Over the past few years the team has extended laboratory experiments to examine solidifying flows at higher fluxes traveling through uniform and irregular channels. At the same time, we have obtained detailed data on distributions of flow surface morphologies, transport conditions, and material properties of basaltic lava produced by several recent eruptions. The proposed work will utilize airborne and ground-based LiDAR to make quantitative and comprehensive measurements of flow features and surface morphologies. It is expected that these data will lead to the development of surface analysis techniques that may have broad application within the Earth Sciences. They will use data to examine down-flow evolution of flow features such as: flow thickening and spreading, channel development, and solid crust thickening. Sampling of the same flows will allow the evaluation of thermal and rheological evolution as it relates to morphological changes. It is further proposed to evaluate current theoretical models (both mechanical and thermal) and identify their strengths and weaknesses. Based on these results, the team will conduct laboratory experiments to help address gaps in our understanding. Ultimately, this work will help unify the disparate approaches that have been taken to understand the physical processes of lava flow emplacement, improving our ability to both predict the behavior of active lava flows and learn about past volcanic activity that is recorded in solidified lava flows.

火山活动地区喷发的熔岩流对财产和基础设施造成相当大的危害，促使该项目了解熔岩流安置的物理原理并提高我们预测其行为的能力。对熔岩流动力学的基本控制来自于它们的流变性，它从喷发时的流体状变化到就位时的固体状。人们通过考虑流动的机械或热演化来研究这种复杂的行为，但很少将这些方法耦合起来。这项拟议的工作旨在通过开发量化熔岩流形态的新方法来将这两种并行方法联系起来，该形态记录了熔岩的耦合热和机械演化。建议使用机载和地面激光测绘技术来构建高分辨率（从 1 cm 到 ~ 1 m）地形图，通过这些地形图，我们可以解析熔岩表面上的单个碎屑、熔岩通道/堤坝和流动边缘等特征。形态学观察将与熔岩物理特性的实验室测量以及使用模拟熔岩流动行为的模拟材料进行的物理实验相结合。综合实验和观测将用于测试和完善流动安置的预测模型。实地考察将在两个地点进行：莫纳罗亚火山和俄勒冈喀斯喀特。这些地点提供了一系列初始熔岩成分和喷发样式，使结果广泛适用于全球火山活动区域。在侵位过程中，熔岩流产生粘性和粘弹性流变，与凝固的地壳相结合，对变形产生复杂的响应。因此，流动安置模型必须考虑流动的机械历史和热历史。力学模型包括粘性流体和宾汉屈服强度流体的重力扩散。热模型主要关注玄武岩熔岩通道，特别是随着固体表面覆盖范围的增加而降低的流动冷却速率，同时通过确定固体地壳的拉伸破坏标准来检查凝固对流动动力学的作用。直到最近，连接热和动力状态的模型还仅限于径向扩散状态下的低雷诺数（低通量）流动。在过去的几年里，该团队扩展了实验室实验，以检查通过均匀和不规则通道的更高通量的凝固流。同时，我们还获得了近期几次喷发产生的玄武岩熔岩的流面形态分布、输送条件和物质特性的详细数据。拟议的工作将利用机载和地面激光雷达对流动特征和表面形态进行定量和综合测量。预计这些数据将促进表面分析技术的发展，这些技术可能在地球科学领域得到广泛应用。他们将使用数据来检查流动特征的向下流动演化，例如：流动增厚和扩散、河道发育和固体地壳增厚。对相同流进行采样将能够评估与形态变化相关的热和流变演化。进一步建议评估当前的理论模型（机械和热）并确定其优点和缺点。根据这些结果，该团队将进行实验室实验，以帮助解决我们理解上的差距。最终，这项工作将有助于统一用于理解熔岩流就位物理过程的不同方法，提高我们预测活跃熔岩流行为和了解凝固熔岩流中记录的过去火山活动的能力。