• Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC


Paper No. 8
Presentation Time: 3:30 PM


DINIEGA, Serina, Jet Propulsion Laboratory, M/S 183-401, 4800 Oak Grove Drive, Pasadena, CA 91109, SMREKAR, Suzanne E., Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 183-501, 4800 Oak Grove Dr, Pasadena, CA 91109, ANDERSON, Steven W., MAST Institute and the Department of Earth and Atmospheric Sciences, University of Northern Colorado, Greeley, CO 80639 and STOFAN, Ellen R., Proxemy Research, Bowie, MD 20715,

As lava viscosity can change 1-2 orders of magnitude due to small changes in temperature, several studies have predicted the formation of low-viscosity/high-temperature “fingers” (similar to a Saffman-Taylor type instability) within an initially near-uniform flow. We examine the onset and evolution of such fingers within a uniform lava sheet flow due to an influx of lava with slightly-variable temperature. We assume Hele-shaw-type geometry (depth << other dimensions), Newtonian and laminar fluid flow, a simple Nahme’s exponential law relating temperature and viscosity, and radiative heat-loss through the flow’s upper surface. Through the use of numerical simulation and steady-state analysis of model equations, we identify solutions that would provide pahoehoe lava flows with a natural mechanism for the formation of lava channels/tubes within a sheet lava flow. Preliminary results indicate that flow-focusing occurs rapidly due to the thermo-viscosity relation, but zones of hotter flow commonly settle into a new steady-state and it is difficult to create perpetually-lengthening hot-fingers of lava (which seem more physically similar to lava tubes). This suggests that additional and/or discontinuous physical processes (such as decreasing radiative rates due to thickening of the surface crust or crystallization abruptly retarding flow within lower-temperature regions) may play important roles in the continued growth of preferred flow zones. This work has application to both Earth and planetary volcanology studies as pahoehoe lava flows dominate terrestrial basaltic lavas and the eruption/emplacement mechanics that yield long lava flows on the Earth and other planetary bodies (e.g., Mars) are not yet well understood.
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