Alaska Volcano Observatory

Several different methods are pictured making concurrent measurements of the composition of gas plumes originating from several large (~10m diameter) pits in the SE flank fumarole field of Trident Volcano. The yellow box on the right is a portable multi-GAS instrument, which continuously measures concentrations of water vapor, CO2, SO2, and H2S every second and writes the measurements to an on-board datalogger. The gray box on the left is an active mercury sampler that uses a pump to pull the gases through a trap that is later analyzed in a lab. The active sampler is plugged into a power supply (the small black box in the middle) to run the pump. The small blue container mounted to a stake on the left is a passive mercury sampler, which collects gases without the use of a pump, by exposing the sampler to the plume and allowing gases to diffuse in from the atmosphere and adsorb onto the sampler surface. The passive sampler is exposed to the plume for a period of time and later sent to a lab for analysis.

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Credit: Image courtesy of AVO/USGS.
Use Restriction: Please cite the photographer and the Alaska Volcano Observatory / U.S. Geological Survey when using this image.
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