According to a Reuters News Report, researchers on April 23 said they used a technique called seismic tomography to produce for the first time a complete picture of the volcanic “plumbing system” at Yellowstone, from the Earth’s mantle up to the surface.

The previously unknown reservoir of hot, partly molten rock is big enough to fill up the Grand Canyon 11 times, scientists say. Scientists already knew of a large magma chamber under Yellowstone that fed the eruptions 2 million, 1.2 million and 640,000 years ago. The new study, published in the journal Science, revealed a second, deeper reservoir 4.5 times larger.

Yellowstone National Park, which straddles the borders of Wyoming, Idaho and Montana, and boasts a remarkable array of geothermal features including geysers, mudpots, steam vents and hot springs, sits atop a supervolcano.

“The existence of the second magma chamber does not make it any more or less likely that a large volcanic eruption at Yellowstone will occur. These findings do not change the current volcanic hazard at Yellowstone,” University of Utah seismologist Jamie Farrell told Reuters. “However, these new findings do provide us, and other researchers, the information needed to gain a better understanding of how magma moves from the mantle to the surface,” Farrell added.

University of Utah geology and geophysics professor Fan-Chi Lin said the blob-shaped lower magma reservoir in Earth’s lower crust is located 12 to 28 miles under Yellowstone, with a volume of 11,500 cubic miles, or 11.2 times the volume of Arizona’s Grand Canyon.