Understanding the Yellowstone Volcanic System through Application of Magnetotelluric and Seismic methods

At crustal depths, geophysical studies of the Yellowstone volcanic system are most commonly designed to investigate the distribution of magmatic fluids in the subsurface. Gaining insight into the structure, temperature, composition, and the presence and nature of fluids in a volcanic system can be ambiguous when making interpretations based on a single geophysical parameter. Since seismic and magnetotelluric (MT) data are sensitive to different properties of the subsurface, interpretation of spatially coincident seismic and electrical resistivity models can help resolve these ambiguities. We are currently engaged in a multi-disciplinary (MT and seismic) study of the Yellowstone region that aims to understand the origin and location of magmatic fluids at upper mantle/lower crustal depths; the preferred path of migration for these magmatic fluids into the mid- to upper-crust; the resulting distribution and composition of the magma reservoir and associated surface hydrothermal expressions; and implications for future volcanism at Yellowstone. This study includes modeling of the resistivity structure at Yellowstone via inversion of both wideband and long-period MT data. Wideband data were collected at densely spaced sites throughout the Yellowstone region in summer 2017. Long period MT data were collected as part of the EarthScope Magnetotelluric Transportable Array. The total set of MT data is being inverted in order to obtain the 3D resistivity structure of the region from upper mantle through upper crustal depths. Concurrent with these modeling efforts, we are carrying out a joint inversion of surface and body-wave data from Yellowstone in order to obtain the P- and S-wave crustal velocity structure. The resulting resistivity and velocity models of Yellowstone are spatially coincident, which allows for joint interpretation of the region in terms of both geophysical parameters. Such joint interpretation will help to more accurately constrain the distribution of hydrothermal and magmatic fluids within the Yellowstone volcanic-hydrothermal system, as well as the structure and thermal properties of that region.