Abstract Bubbles are known to have a dramatic effect on lava rheology, but their impact on lava flow run out distance has not been extensively investigated. To quantify bubble effects on basaltic lava flow emplacement, we conducted a series of large-scale two-phase (melt+bubbles) experiments at the Syracuse University Lava Project facility. In this study, nine basaltic lava flows with low to intermediate vesicle contents (approximately 3-24 vol%) were emplaced over gently sloping (4°-9°) dry sand surfaces. Their velocities were measured by particle image velocimetry, and their bulk viscosities were calculated using Jeffreys' equation. Comparison with melt-only viscosities (calculated through the GRD model) allowed the isolation of the effect of bubbles on the viscosity of the experimental flows. We find that within the investigated range of vesicularities, bubbles increase the relative viscosity of the experimental flows by up to an order of magnitude. The increase appears to be steeper for sheet flows than for lobate and toey flows. Our results, which quantitatively assess the effect of bubbles on the rheology of basaltic lava flows, will provide a basis for the refinement of models for multi-phase flows that are fundamental to accurately forecasting the emplacement of lava flows.

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气泡对玄武岩熔岩流流变学的影响：来自大规模两相实验的见解

摘要 众所周知，气泡对熔岩流变学具有显着影响，但它们对熔岩流出距离的影响尚未得到广泛研究。为了量化气泡对玄武岩熔岩流侵位的影响，我们在雪城大学熔岩项目设施进行了一系列大规模两相（熔体+气泡）实验。在这项研究中，九个具有低到中等囊泡含量（大约 3-24 vol%）的玄武岩熔岩流被放置在平缓倾斜 (4°-9°) 的干燥砂表面上。它们的速度是通过粒子图像测速法测量的，它们的体积粘度是使用杰弗里斯方程计算的。与仅熔体粘度（通过 GRD 模型计算）的比较允许隔离气泡对实验流粘度的影响。我们发现在研究的气泡范围内，气泡使实验流的相对粘度增加了一个数量级。片状流动的增加似乎比叶状和脚趾状流动的增加更陡峭。我们的结果定量评估了气泡对玄武岩熔岩流流变学的影响，将为改进多相流模型提供基础，这些模型对于准确预测熔岩流的侵位至关重要。