One of the world’s most closely monitored volcanic systems lies beneath Yellowstone National Park’s bubbling geysers and steaming mud pots. Now, a team of geoscientists has uncovered new evidence about how this mighty system behaves and what might keep it from erupting.

A new study shows a volcanic eruption of Yellowstone may be even less likely than we thought: Scientists have discovered a magma cap that may play a role in relieving volcanic pressure underground.