Fluid movement in the subsurface of active volcanoes is frequently thought to produce abundant seismicity (i.e. earthquakes); however the actual type of fluid, including magma, volcanic gases, or hydrothermal waters, and the implications of the fluid movement cannot currently be constrained from seismic data. Knowledge of the type of fluid/s in the subsurface is critical for both forecasting volcanic eruption and estimating the explosivity of the impending eruption. Through comparison of high temporal resolution measurements of volcanic gas composition and seismicity, it may be possible to identify the type of fluid associated with unique seismic signatures. The ability to identify magma movement from seismic data will enable scientists to better determine the likelihood and/or timing of impending eruptions.
In this project, geochemical measurements of volcanic fluids and complementary seismic data from three historically-active Alaskan volcanoes will be used to: (1) determine the source (i.e. subducted slab, mantle, crust) and flux of volcanic gases, (2) determine proportions of magmatic and hydrothermal fluids within the subsurface, and (3) distinguish trends in gas composition and/or flux that correlate with seismic signatures of fluid movement. Gas composition will be combined with total gas flux to help elucidate subduction and magma generation processes. Daily measurements of gas composition and flux will be compared with seismic data collected over a two-month period to help determine the type of fluid movement associated with certain seismic signals. This project will answer fundamental science questions applicable to GeoPRISMS objectives, specifically regarding the storage, transfer, and release of volcanic fluids, and the relationship between subduction and surface processes.
