HR: 0830h
AN: V21C-0530    [PDF]
TI: Diffuse CO$_{2}$ Degassing From Devils Kitchen, Mt. Hood, Oregon
AU: * Bergfeld, D
EM: dbergfel@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road MS 434, Menlo Park, CA 94025 United States
AU: Howle, J F
EM: jfhowle@usgs.gov
AF: U.S. Geological Survey, 5229 North Lake Blvd, Carnelian Bay, CA 96140 United States
AU: Schmidt, M E
EM: schmidtm@geo.orst.edu
AF: Oregon State University, 104 Wilkinson Hall, Corvallis, OR 97331-5506 United States
AB: Research to quantify diffuse CO$_{2}$ emissions from volcanoes is a useful component of a monitoring program as increases in diffuse CO$_{2}$ emissions have been linked to volcanic unrest. The Devils Kitchen (DK) at Mt. Hood, OR is a $>$ 5000 m$^{2}$ area of steaming ground, located near the summit of the volcano at the terminus of Coalman glacier. Numerous small, sub-boiling gas vents are scattered across the area and soil temperatures at the interior are typically elevated above background. Much of the host rock has been hydrothermally altered to clay, creating a hard packed moist surface of low permeability. At present, there are no fumaroles at DK, however many large fumaroles vent from the nearby Steel Cliffs and Crater Rock. During August 2003, we constructed a grid of 75 sites at DK using 10-m spacing, covering $\approx$ 5,000 m$^{2}$. CO$_{2}$ fluxes were measured using the accumulation chamber method. Soil temperatures were measured at 10-cm depth adjacent to each flux site. Fluxes and temperatures ranged from less than 8 to over 11,000 g m$^{-2}$ d$^{-1}$ and 5 to $88\deg$C, respectively. The average flux at DK was 190 g m$^{-2}$ d$^{-1}$. Applying this average across the sampled area yields total CO$_{2}$ emissions of 0.9 $\pm$ 0.1 t d$^{-1}$. Based on our field mapping after a snowfall, we estimate at least 37,000 m$^{2}$ of thermal ground is present on Mt. Hood. If the flux over these areas is similar to the flux at DK this would indicate diffuse CO$_{2}$ emissions on Mt. Hood are about 7 t d$^{-1}$. This estimate may be conservative as fluxes at several sites at the edge of a large area of steaming ground above Crater Rock were much greater than the maximum flux at DK. Compared to reports of total diffuse CO$_{2}$ emissions on similar volcanoes, our estimate for Mt. Hood is low and may indicate that most of the CO$_{2}$ is emitted from the fumaroles.
DE: 8419 Eruption monitoring (7280)
DE: 8424 Hydrothermal systems (8135)
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting