Tomography from 26 years of seismicity revealing that the spatial extent of the Yellowstone crustal magma reservoir extends well beyond the Yellowstone caldera

The Yellowstone volcanic field has experienced three of Earth's most explosive volcanic eruptions in the last 2.1 Ma. The most recent eruption occurred 0.64 Ma forming the 60 km long Yellowstone caldera. We have compiled earthquake data from the Yellowstone Seismic Network from 1984 to 2011 and tomographically imaged the three-dimensional P wave velocity (Vp) structure of the Yellowstone volcanic system. The resulting model reveals a large, low Vp body, interpreted to be the crustal magma reservoir that has fueled Yellowstone's youthful volcanism. Our imaged magma body is 90 km long, 5-17 km deep, and 2.5 times larger than previously imaged. The magma body extends similar to 15 km NE of the caldera and correlates with the location of the largest negative gravity anomaly, a -80 mGal gravity low. This new seismic image provides important constraints on the dynamics of the Yellowstone magma system and its potential for future volcanic eruptions and earthquakes.