Scientists from the US Geological Survey who breezily informed the public that there’s “nothing to worry about” with regards to the Yellowstone caldera, a supervolcano that should it erupt could cause potentially hundreds of thousands of deaths, should be eating their words.

Since about mid-July, the earth beneath the volcano has been shifting in a sign that magma could be rushing into the caldera’s main chamber. Since then, there have been roughly 2,500 small-scale earthquakes recorded near the volcano, the largest stretch on record. Previous estimates had assumed that the process that led to the eruption took millenniums to occur.

The same estimates that USGS based their warning on.

As the New York Times explains, the Yellowstone caldera is a behemoth far more powerful than your average volcano. It has the ability to expel more than 1,000 cubic kilometers of rock and ash at once, 2,500 times more material than erupted from Mount St. Helens in 1980, which killed 57 people. That could blanket most of the United States in a thick layer of ash and even plunge the Earth into a volcanic winter.

As the Times points out, scientists expect a supervolcano eruption to scar the planet once every 100,000 years.

To reach their conclusion, the team of scientists spent weeks at Yellowstone’s Lava Creek Tuff – a fossilized ash deposit from the volcano’s last supereruption, where they gathered samples and analyzed the volcanic leftovers. The analysis allowed the scientists to pin down changes in the lava flow before the last eruption. The crystalline structures of the rocks recorded changes in temperature, pressure and water content beneath the volcano just like tree rings do.

“We expected that there might be processes happening over thousands of years preceding the eruption,” said Christy Till, a geologist at Arizona State, and Ms. Shamloo’s dissertation adviser. Instead, the outer rims of the crystals revealed a clear uptick in temperature and a change in composition that occurred on a rapid time scale. That could mean the super eruption transpired only decades after an injection of fresh magma beneath the volcano.”

Thanks to this research, scientists are beginning to realize that the conditions that would lead to a supervolcano eruption could emerge during a human lifetime. As the research continues, scientists hope they will be able to spot more signs of a coming eruption.

“It’s one thing to think about this slow gradual buildup – it’s another thing to think about how you mobile 1000 cubic kilometers of magma in a decade,” she said.

While scientists at the USGS have brushed off the threat of a supervolcano eruption, scientists at NASA have at least acknowledged the threat to the US population. The agency has devised a potential strategy to try and defuse an eruption should one appear imminent, though according to several the techniques involved – specifically, pumping water directly into the volcano’s magma chamber – involve significant risks.

But who knows? If the research is accurate, an eruption could emerge as a serious threat to the US – and possibly the global population – population as the fallout kills crops and livestock, causing widespread famine, while clouds of choking ash and debris spread for hundreds, if not thousands, of miles.