What caused the hydrothermal explosion at Yellowstone National Park? Meteorologist explains

Yellowstone National Park visitors were sent running and screaming Tuesday when a hydrothermal explosion spewed boiling hot water and rocks into the air. No one was injured, but it has left some wondering: How does this happen and why wasn't there any warning? 

The Weather Channel's Stephanie Abrams said explosions like this are caused by underground channels of hot water – which also create Yellowstone's iconic geysers and hot springs. 

"When the pressure rapidly drops in a localized spot, it actually forces the hot water to quickly turn to steam, triggering a hydrothermal explosion since gas takes up more space than liquid," Abrams said Wednesday on "CBS Mornings." "And this explosion can rupture the surface, sending mud and debris thousands of feet up and more than half a mile out in the most extreme cases."