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Meet a friend of ours. This friend has been monitoring changes of the ground surface in Yellowstone for decades and is so good that it can detect movement of just a few millimeters in magnitude (just a fraction of an inch). The friend? A continuous GPS station!

Happy New Year! Let's go back and take a look at the top five geologic stories for Yellowstone in 2025.

Number five: Rumors. It was a year of internet rumors, mostly related to animals fleeing the park, and none of which were true.

Just last week, Kīlauea put on another dramatic display of lava fountaining and flows within the caldera, during its 37th episode of this most recent eruption. It doesn't seem like Hawaii and Yellowstone have a lot in common, but actually, those two magmatic systems have a common cause.

The Yellowstone caldera is vast – 45 miles across by 30 miles wide. You could fit over 60 islands of Manhattan in this area. There are deep canyons, like the one on the Yellowstone River, that reveal a complex geologic history. And, forested landscapes and features remind us that this special place is ever-changing.

Picture a Yellowstone eruption. What comes to mind? It’s a huge explosion, right? Like the one that formed the caldera about 631,000 years ago. But the most common form of eruption in Yellowstone isn’t a huge explosion, it’s a lava flow.

Just over one year ago, early morning visitors to Yellowstone’s Black Diamond Pool suddenly found themselves filming a spectacular event. The July 23, 2024 hydrothermal explosion threw material hundreds of feet high, including rocks that were a foot or more across.