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 homogeneousfluid 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.
Additional Publication Details
USGS Numbered Series
A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits
Version 1.0.0 October 2000; Version 1.0.5c November 2013
U.S. Geological Survey
Volcano Science Center, Cascades Volcano Observatory
Report: viii, 53 p.; Visual program description; Readme file; Executable program for Windows 95/98/NT/XP; Fortran source code