Fumarole gas chemistry analyses from Baker, Hood, and Lassen have been obtained by two methods. The traditional ‘gas vacuum flask’ method has been used for decades, and annually in Baker’s Sherman Crater for the past few years. This method collects gas from discrete fumarole vents. The delicate glass flasks must then be backpacked out and sent off to Menlo Park California for chemical analysis.
A newer method uses a passive multi-gas ‘sniffer’ system, designed by Peter Kelly at the Cascade Volcano Observatory. This method uses a set of gas samplers with built-in analytic software, and is self-contained inside a backpackable hard case. The experimental ‘sniffer’ has been deployed at Baker, Saint Helens, Hood and Lassen over the past year. It passively analyses gas concentrations from within fumarole plumes. At Sherman Crater, for instance, the portable analyzer was placed a few meters away from a cluster of many very dynamic fumaroles, and inevitably sampled gas from all of them, as well as ambient gas from more distant vents in the crater.
An abstract comparing the data obtained by the two methods has been submitted to the December annual meeting of the American Geophysical Union (AGU) in San Francisco. The authors are Peter Kelly, Cynthia Werner, William Evans, and Stephen Ingebritsen, all of the US Geological Survey, and Dave Tucker (Western Washington University).
The abstract is posted at the top of the ‘abstracts’ page over on the main MBVRC data website: http://mbvrc.wwu.edu/abstracts/index.php
The comparison of gas concentrations collected by the two methods uses the ratio of CO2 to H2S concentrations- these are the principal gases after water vapor. The passive automatic sniffer obtained data readings comparable to the vacuum flask method. However, analysis of gas samples captured in the traditional method determines a variety of other fumarole gases, including He, H2, O2, Ar, N2, and CH4.
Quite a number of volunteer mountaineers have helped gather this data at Baker over the past 5 years or so. Many thanks to all of you. Baker sampling, including use of the new ‘sniffer’, will continue for the foreseeable future.