New research indicates it likely won’t blow today, but one region on Yellowstone’s northeastern side is likely to host liquid magma in the long term, possibly fueling future eruptions hundreds of thousands of years from now.
Yellowstone’s melted magma lurks in four separate reservoirs within the crust of the caldera. The western reservoirs do not touch the deep mantle rocks that would heat them from below so they will likely start to cool and solidify. But to the northeast, mantle rocks are heating the magma trapped in the crust keeping them liquid and eruptable.
Using measurements of earthquake waves and magnetotellurics (measurements of subterranean magma magnetic fields) researchers mapped four main hidden pockets of magma that together contain more liquid magma than was present during large, caldera-forming eruptions at Yellowstone in the past (2.8 MYA, 1.3 MYA and 640,000 years ago). These magma pockets rest as deep as about 6 or 7 miles below the surface, but only in the northeastern region of the caldera is the magma in touch with hot mantle rock that will keep the magma liquid in the long term. Despite the large volume of magma pooling below Yellowstone, the caldera isn’t likely to erupt anytime soon. The magma sits in pore spaces in solid rock, much like water in a sponge. The estimated fraction of magma filled pores is 20% or less, but only when more than 40% of pore spaces are filled can the magma link up, get mobile and start erupting. But that could change over tens of thousands of years as mantle rock warms the northeastern magma pools. Exactly how long that will take, or if it will happen before the mantle rocks in the northeastern region of Yellowstone lose contact with its magma reservoir, remains unknown.
Condensed from a Live Science article by