Yellowstone supervolcano fed by larger plume

BBC : The Yellowstone Caldera feeds the hot springs, mud pots, and geysers associated with Yellowstone National Park. Seismic images created in 2009 of the subterranean molten plume showed it dipping downward from Yellowstone at a 60-degree angle and extending about 150 miles west-northwest to a point about 410 miles underground, under the Montana-Idaho border. Michael Zhdanov and colleagues at the University of Utah in Salt Lake City have used electrical conductivity to create new images of the plume; they found that it dips less steeply, at about 40 degrees, and extends about 640 miles from east to west. The two sets of images may look different because they measure different things; seismic images highlight materials that slow seismic waves, and geoelectric images highlight fluids that conduct electricity. The difference may indicate that there are more fluids underground than previously thought, and that the smaller region imaged by seismic waves may be enveloped by a broader region of partly molten rock and other liquids.