A new kind of image suggests the giant volcanic plume lying under Yellowstone National Park is even bigger than previously thought.
University of Utah geophysicists used the electrical conductivity of the huge tongue of hot and partly molten rock to create an image. That image suggests the plume is even bigger than it appears in earlier images made with seismic waves.
"It's like comparing ultrasound and MRI in the human body; they are different imaging technologies," geophysicist Michael Zhdanov, principal author of the new studyÂ and an expert on underground structures, said in a news release from the university.
A 2009 seismic study showed the plume dips downward from Yellowstone at an angle of 60 degrees and extends 150 miles west-northwest to a point at least 410 miles under the Montana-Idaho border - as far as seismic imaging could "see."
In the new study, images show the electrically conductive part of the plume dipping more gently, at an angle of perhaps 40 degrees to the west, and extending perhaps 400 miles from east to west. The geoelectric image can "see" only 200 miles deep.
The University of Utah study will be publishedÂ soon in the journal Geophysical Research Letters.