Emission rates of CO2, SO2, and H2S, scrubbing, and preeruption excess volatiles at Mount St. Helens, 2004-2005

Terrence M. Gerlach; Kenneth A. McGee; Michael P. Doukas

doi:10.3133/pp175026

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Emission rates of CO2, SO2, and H2S, scrubbing, and preeruption excess volatiles at Mount St. Helens, 2004-2005

Terrence M. Gerlach·Kenneth A. McGee·Michael P. Doukas

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Abstract

Airborne surveillance of gas emissions began at Mount St. Helens on September 27, 2004. Reconnaissance measurements--SO 2 column abundances and CO 2 , SO 2 , and H 2 S concentrations--showed neither a gas plume downwind of the volcano nor gas sources within the crater. Subsequent measurements taken during the period of unrest before the eruption began on October 1 and for several days after October 1 showed only small point sources of gas within the crater. These sources defined a pattern of scrubbed degassing that evolved from near-zero emissions, to scattered CO 2 -only sources, to growing sources of CO 2 with minor H 2 S and SO 2 , and finally to myriad sources of CO 2 with increasingly SO 2 - dominant sulfur gases. Scrubbing strongly hydrolyzed SO 2 but also affected CO 2 and H 2 S.

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Source-reported bounding extent: 46.161175° to 46.233792° latitude; -122.238678° to -122.131489° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Terrence M. Gerlach, Kenneth A. McGee, Michael P. Doukas. 2008. Emission rates of CO2, SO2, and H2S, scrubbing, and preeruption excess volatiles at Mount St. Helens, 2004-2005. https://doi.org/10.3133/pp175026

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