"The magma reservoir is at least 50 percent larger than previously imagined," University of Utah's Jamie Farrell told the Salt Lake City gathering.
Farrell told LiveScience.com that he analyzed nearby earthquakes to build a better picture of Yellowstone's magma chamber. He described the chamber as a "mutant banana, with a knobby, bulbous end poking up toward the northeast corner of Yellowstone, and the rest of the banana angling to the southwest."
University of Utah geophysicists and computer scientists also unveiled the first large-scale geoelectric image of the Yellowstone hotspot, with yellow and red indicating higher conductivity and green and blue indicating lower conductivity.
Previously, researchers theorized the magma beneath Yellowstone was in separate blobs.
Scientists said the last caldera (ancient super volcano) eruption was 640,000 years ago. Smaller eruptions occurred as recently as 70,000 years ago.