Open-File Report 00-209
This report presents a model that calculates flow properties (pressure, vesicularity, and some 35 other parameters) as a function of vertical position within a volcanic conduit during a steady-state eruption. The model idealizes the magma-gas mixture as a single homogeneous fluid and calculates gas exsolution under the assumption of equilibrium conditions. These are the same assumptions on which classic conduit models (e.g. Wilson and Head, 1981) have been based. They are most appropriate when applied to eruptions of rapidly ascending magma (basaltic lava-fountain eruptions, and Plinian or sub-Plinian eruptions of intermediate or silicic magmas) that contains abundant nucleation sites (microlites, for example) for bubble growth.
First posted May 08, 2008
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Mastin, L. G., and Ghiorso, M. S., 2000, A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits (vers. 1.05b, April 2008): U.S. Geological Survey Open-File Report 00-209, 61 pp, https://pubs.usgs.gov/of/2000/0209/.
Model assumptions and limitations
First-Order Testing the model
Using the Windows-based system
Running the model from the command line