Skip Links

USGS - science for a changing world

Open-File Report 00-209

A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits

By Larry G. Mastin and Mark S Ghiorso

Thumbnail of and link to report PDF (870 KB)Summary

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

Reposted November 15, 2013

For additional information:
Contact CVO 
Volcano Science Center, Cascades Volcano Observatory 
U.S. Geological Survey 
1300 SE Cardinal Court, Building 10, Suite 100 
Vancouver, WA 98683-9589

Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

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,



Model overview

Model assumptions and limitations

Model setup

First-Order Testing the model

Using the Windows-based system

Running the model from the command line

Closing comments

Accessibility FOIA Privacy Policies and Notices logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: Contact USGS
Page Last Modified: Wednesday, December 07, 2016, 06:16:18 PM