TY - JOUR
T1 - The effect of bubbles on the rheology of basaltic lava flows
T2 - Insights from large-scale two-phase experiments
AU - Soldati, A.
AU - Farrell, J. A.
AU - Sant, C.
AU - Wysocki, R.
AU - Karson, J. A.
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/10/15
Y1 - 2020/10/15
N2 - 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.
AB - 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.
KW - basaltic lava flows
KW - bubbles
KW - large-scale experiments
KW - two-phase rheology
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U2 - 10.1016/j.epsl.2020.116504
DO - 10.1016/j.epsl.2020.116504
M3 - Article
AN - SCOPUS:85088982012
SN - 0012-821X
VL - 548
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
M1 - 116504
ER -