The volcano under Yellowstone National Park, which scientists in April said was larger than previously believed, has now been found to exceed even the earlier expectations.

A sound wave study of the magna chamber under the park has found that it measures 55 miles by 20 miles and contains over 140 cubic miles of molten rock. The team from the University of Utah called their discovery “astounding.”

They also said if the volcano were to erupt it would wipe out America and would devastate life in the rest of the world.

The scientists say the volcano erupts every 700,000 years and that the last time the volcano roared was about 650,000 years ago.

In addition, about twenty smaller super volcanoes have been discovered nearby on the Utah/Nevada border.