So you’ve heard about the Yellowstone volcano. But where is it? It’s the shear size of the Yellowstone volcano that makes it so hard to discern. Most people look for a cone-shaped mountain when you say “volcano.” Yellowstone has several of those. But the Yellowstone volcano is much larger than that. The whole area is a massive high plain domed upward due to the heat of magma below. That accounts for the park’s high elevation which averages 8000 feet above sea level.
The Yellowstone volcano has erupted many times over millions of years but the last three eruptions left calderas or craters in the park. The last eruption over 640,000 years ago left a caldera 30 by 45 miles wide.
Lava continued to seep out of the volcano after the last eruption and some of those lava flows filled in portions of the caldera so it’s not as deep as it once was. Much of the park is actually in the crater and the large size makes it difficult to tell you are in the crater of a big volcano.
There are a few places in the park where you can see the caldera—Gibbon Falls, Washburn Hot Springs Overlook, from the top of Mount Washburn. It is probably best seen from outer space. From that vantage point, you would actually see that the Yellowstone volcano or hotspot is responsible for a series of calderas that stretch from the park, south and west to Nevada.
The hotspot or magma chamber below ground has erupted periodically over the last 16 million years as the continental plate has slowly drifted over the top of it, creating a string of volcanic eruptions and calderas.
Yellowstone sits atop the magma chamber today and though it may be difficult to conceive the volcano, the plethora of hot springs and geysers are a good reminder that it is there, just under our feet.