Michael Poland

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.

Grand Prismatic Spring is the largest hot spring in the US, and one of the largest in the world. The boiling lake was named for the spectacular array of colors along its rim.

There’s a lot of hot water in Yellowstone. What’s it heated by? The magma chamber beneath the surface, of course!

This video, recorded by a webcam, shows a small eruption from Black Diamond Pool in the Biscuit Basin subbasin of Upper Geyser Basin, Yellowstone National Park, at 8:39 p.m. MDT on May 31, 2025.  The pool was the site of a hydrothermal explosion on July 23, 2024.

If you want to find a lava flow in Yellowstone, look to the trees! The vegetation is telling us more than you might think.

YVO Scientist-in-Charge Mike Poland reveals how vegetation can be used to map geology in this month's update from the Yellowstone Volcano Observatory.

Well look at this mess! What’s going on? 

We’re just south of Mammoth Hot Springs at a place informally known as the Hoodoos. The official designation for the area is Silver Gate, named by an early Yellowstone National Park visitor because of the way the road wound between the closely spaced white and gray boulders. 

Is it true roads in Yellowstone National Park are melting? Whatever you might have heard, it's nothing new and it's not due to increased volcanic activity. Get up-to-speed in this month's update from the Yellowstone Volcano Observatory (March 2025).

You've probably seen videos of black smokers on the ocean floor, where hydrothermal fluids vent from chimneys. In Yellowstone’s Monument Geyser Basin, you can see similar features right at the surface, and they likely formed in much the same way. Watch to learn more.