YVO Monthly Video Update -- September 2, 2025 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. Yellowstone’s most recent lava flow occurred about 70,000 years ago. The type of lava that erupted is not what you might see in Hawaii with its fountains of molten rock and fast-flowing channels of basalt. In Yellows

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