A massive supervolcano lurks under the surface of Yellowstone National Park, and an alarming new report indicates that it could blow a lot more quickly than scientists realized. Don’t worry, it’s almost certainly not going to happen in our lifetimes, but it’s a fascinating finding that could change our understanding of this incredible national park.

The gigantic magma reservoir underneath Yellowstone that results in much of the natural beauty of the park is also incredibly deadly, as it could cause an eruption so large it could trigger a mass extinction event worldwide. And while there’s no sign that it’s close to erupting, it would take just a few decades for it to happen rather than hundreds of years, so we wouldn’t get nearly the amount of warning we thought we would.

Yellowstone is an extremely well monitored volcano, perhaps the most well monitored in the world, so even if things suddenly started shifting dangerously toward eruption, we’d have decades of advance notice. Of course, once it erupts, there really won’t be any place to hide on Earth.

“The loosely defined term “supervolcano” has been used to describe volcanic fields that produce exceptionally large volcanic eruptions,” reads a Wikipedia excerpt. “Thus defined, the Yellowstone Supervolcano is the volcanic field which produced the latest three supereruptions from the Yellowstone hotspot; it also produced one additional smaller eruption, thereby creating West Thumb Lake 174,000 years ago. The three supereruptions occurred 2.1 million, 1.3 million, and approximately 630,000 years ago, forming the Island Park Caldera, the Henry’s Fork Caldera, and Yellowstone calderas, respectively. The Island Park Caldera supereruption (2.1 million years ago), which produced the Huckleberry Ridge Tuff, was the largest and produced 2,500 times as much ash as the 1980 Mount St. Helens eruption. The next biggest supereruption formed the Yellowstone Caldera (~ 630,000 years ago) and produced the Lava Creek Tuff. The Henry’s Fork Caldera (1.2 million years ago) produced the smaller Mesa Falls Tuff but is the only caldera from the Snake River Plain-Yellowstone hotspot that is plainly visible today.”