Huge chunk of Yellowstone National Park, the size of Chicago, is 'breathing' in and out due to magma trapped underneath the surface

• An area at the center of the Norris Geyser Basin was found to inflate and deflate
• Experts have determined a intrusion of magma under the surface is to blame
• Magma became trapped at the top and pushed the rocks up above it
• The magma has since receded, putting the pulsating on pause for now 

An area the size of Chicago in Yellowstone National Park has been inflating and deflating by several inches over the past decade

The Norris Geyser Basin, the oldest, hottest and most dynamic thermal area in the park, was observed to rise 5.9 inches each year from 2013 to 2015 - an unusual event that left researchers baffled.

Now, using satellite radar and GPS data, experts have determined the ground deformation was caused by magma intrusions trapped below the basin's surface.

As magma made its way to the surface, the pressure pushed rocks above it up and created an erratic pulsating effect, according to National Geographic.

This is the first time the scientific community has been able to track an entire episode of magma intrusion, which they say is a common occurrence throughout Yellowstone. 

Yellowstone National Park sits in the northwest region of Wyoming and is home to bursting geysers, steam vents and bubbling pools.