Collaborative Research: Magnetotelluric and Seismic Investigations of the Distribution of Magmatic and Hydrous Fluids Beneath Yellowstone

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Collaborative Research: Magnetotelluric and Seismic Investigations of the Distribution of Magmatic and Hydrous Fluids Beneath YellowstoneNon-technical descriptionThe Yellowstone volcanic system in Idaho, Montana, and Wyoming has produced three massive volcanic eruptions in the past 2.1 million years, the most recent 640,000 years ago. Smaller eruptions followed until 70,000 years ago, and today, Yellowstone's volcanic system hosts a dynamic hydrothermal system with thousands of small magnitude earthquakes occurring annually. In this project, a team from the University of Wisconsin-Madison and Oregon State University is deploying a network of sensitive magnetotelluric (MT) equipment, which record natural variations in Earth's geomagnetic and geoelectric fields, in and around Yellowstone National Park. The team is using MT data to sense small changes in conductivity of the crust and mantle and, by combining MT and seismic measurements of the structure beneath Yellowstone, the team will infer the distribution of fluids in the magmatic system; how magma is stored at Yellowstone; and how mobile it is within the region. This has implications for future volcanic activity at Yellowstone and potential hazards such activity might pose.This project is also fostering the career of principal investigator Ninfa Bennington, an early career female scientist, and involves field work by both graduate and undergraduate students from traditionally underrepresented groups. The team is creating outreach materials that will be shared with more than 40,000 people per year via interactive kiosks at the Geology Museum of the University of Wisconsin-Madison, and is developing a smartphone app to share this content with an even broader audience. In addition, they are working with Yellowstone National Park to create content detailing the field work carried out, and the results of the project, for the National Park Web site. These efforts will ensure the results from this project reach a wide audience.Technical Description of ProjectPrevious seismic and magnetotelluric (MT) studies of the crust and upper mantle beneath Yellowstone (YS) have provided insight into the origin and migration of magmatic fluids into the YS crustal volcanic system. However, important questions remain concerning the generation of magmatism at YS and the migration and storage of these magmatic fluids within the crustal volcanic system. The research team has developed three competing hypotheses describing active volcanism at YS, which include different explanations for: 1) the origin and location of magmatic fluids at upper mantle/lower crustal depths 2) the preferred path of migration for these magmatic fluids into the mid- to upper-crust, 3) the resulting distribution of the magma reservoir, 4) the composition of the magma reservoir, and 5) implications for future volcanism at YS. To evaluate these hypotheses for active volcanism at YS, the team is conducting a high-resolution MT survey in the YS region, and is combining those observations with existing data to invert for the 3D resistivity structure in the crust and upper mantle underneath YS. The team is also separately inverting seismic data to determine the seismic velocity structure in the same region using multi-scale techniques. The resulting models are sensitive to different properties of the subsurface (e.g., MT to presence of melt and seismic velocity to increased temperature), and therefore provide independent structural constraints. The team will combine these independent, spatially coincident models through joint interpretations test their hypotheses about the distribution and behavior of magmatic and related fluids in the Yellowstone magmatic system.