Linking geodetic observations with gas emissions to characterize magmatic activity at a subduction zone volcano: Mt. Baker (Washington)

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Research at erupting volcanoes has shown that high surface temperatures, gas emissions, and geodetic and seismic unrest are signatures of magmatic activity at depth. Few studies have correlated such geophysical and geochemical measurements at non-erupting volcanoes. This project is a 2-year pilot study to investigate the relationship between volcano degassing and magmatic activity by collecting gas samples and geodetic measurements at Mount Baker volcano, Washington. The volcano has shown no signs of historical seismic unrest, yet actively emits both carbon dioxide and hydrogen sulfide at rates similar to other volcanoes where intrusions have been inferred from seismicity. Mount Baker is of additional interest because of an unexplained increase in gas emissions and thermal activity that occurred in 1975. The goals of this study are to gather sufficient data to discern whether the investigators will be able to characterize the patterns of gravity change and surface deformation at a quiescent, degassing, subduction zone volcano, and evaluate the relationship between gas emission and geodetic changes over time. The researchers will reoccupy USGS electronic distance meter (EDM) sites, last surveyed in 1983, with GPS and also conduct microgravity studies. The principle investigator will collaborate with US Geological Survey colleagues to collect repeat airborne gas flux measurements over the volcano and collect fumarole gas samples and measure temperatures on the ground. Gas will be analyzed for composition and helium isotope ratios. When these datasets are considered together with geodetic observations, much can be learned about the magmatic system at Mount Baker and other volcanoes by analogy.The integration of GPS and gravity measurements with gas geochemistry has the potential to revolutionize our understanding of volcanic processes. However, few previous studies have attempted to correlate thermal and gas emissions with geodetic data at quiescent volcanoes; therefore, therefore this research may have a significant benefit to the understanding of volcanic processes and, potentially, hazards. Further, the results may be used to infer the mechanisms that caused the gas/thermal unrest at Mount Baker in 1975. Mt. Baker represents the most significant volcanic hazard to northwest Washington and the lower mainland of British Columbia, home to more than 2.5 million people. Long-term societal benefits may include enhanced ability to predict the character of future volcanic activity.