Materials Underneath Yellowstone Caldera Mapped

Associated Press

Scientists have mapped the size and composition of the large volcanic plume that reaches 200 miles beneath the surface of Yellowstone National Park.

They have created images using electric and magnetic sensors.  They say the material underneath the surface caldera is largely a salty, liquid fluid similar to seawater.  There is also solid rock and melted rock.

The plume rises to the surface at a 40 degree angle, and is about 400 miles across.

The caldera was the scene of a massive volcanic eruption more than 600,000 years ago.

But, they say the new data does not really give any clues about when the next eruption might happen.