7.5K views · 219 reactions | One of the world's largest supervolcanoes erupted 2.1 million years ago in Yellowstone, and then twice more there at intervals of roughly 660,000 years. Are we due for another one soon? Tune in to Yellowstone Supervolcano and more shows featuring historic disasters, airing all day long. | Smithsonian Channel Aviation Nation | Facebook

For this month's video update of the Yellowstone Volcano Observatory, we'd like to introduce you to 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! There are dozens of continuous GPS stations throughout the Yellowstone region, and they show us that the ground in Yellowstone is always changi