Yellowstone has the world's largest collection of geysers, and it has the underground plumbing to prove it. Scientists have announced that the volcanic activity beneath the National Park's surface may be far bigger and better connected than once thought.

The National Park is home to hot springs, mudpots, fumaroles and geysers, so it's not surprising that it has quite a bit of volcanic activity under the ground. Known as a hotspot, a massive volume of molten magma is located beneath Yellowstone. This plume of superheated rock rises from Earth's mantle, punching through the continent's crust as North America has slowly drifted over it. The phenomenon has left a trail of calderas created by massive volcanic eruptions in its wake; the most recent occurred about 640,000 years ago.

Yellowstone is infamous for its potential for a "super eruption." When the Huckleberry Ridge eruption in Yellowstone occurred about 2 million years ago, it darkened the skies with ash from southern California to the Mississippi River. It was one of the largest eruptions to have occurred on our planet. Understanding the volcanic activity of this location is therefore crucial for predicting future eruptions.

So how did researchers find out about the new size of this hotspot? They analyzed earthquakes, examining the seismic waves as they travelled through the earth. Since these waves change speed depending on whether they travel through molten or solid rock, the scientists were able to determine exactly how big the mass of molten material beneath the surface is.

"We are getting a much better understand of the volcanic system of Yellowstone," said Jamie Farrell, a seismology graduate student at the University of Utah, in an interview with LiveScience.com. "The magma reservoir is at least 50 percent larger than previously imagined."

The reservoir isn't just bigger; it's also more connected. The researchers discovered that instead of individual pockets, the underground magma is centered in one giant mass. About 37 miles long and 18 miles wide, the magma helps power the volcanic activity seen at the park.

The new findings could allow scientists to better predict future eruptions in the area. In addition, it has given them some more insight into what makes Yellowstone and its geysers tick.

The findings were reported at the Seismological Society of America's annual meeting.