The explosion was relatively small, but still triggered noticeable changes to the area.

Another geothermal explosion has occurred at Yellowstone National Park, highlighting the unstable nature of the reserve's extensive volcanic network, the USGS said.

The explosion was relatively small, but still triggered noticeable changes to the area.

A churning pool of water has opened up in Yellowstone National Park – just two days after scientists were walking around on the exact patch of ground.