With its raging rivers, sprawling canyons and lush forests, Yellowstone National Park is an absolute treasure, but deep beneath its scenic surface lies a hell just waiting to be unleashed , Using computer modeling, researchers have simulated the conditions beneath North America's largest super volcano – by discovering a zone that could control the movement of magma that flows out of the mantle.
A huge reservoir of magma lurks beneath Yellowstone National Park, but it's been 630,000 years since this hidden super volcano has experienced a super eruption, and 70,000 years since its last major lava flow. Scientists are not sure if and when the next eruption will take place, but should it happen, lava would emanate from the Yellowstone caldera and cover an area of 30 to 40 miles.
New research published this week in Geophysical Research Letters furthers our understanding of magma bodies located beneath Yellowstone National Park and how this extensive lava-filled pipeline system actually works. Using computer modeling, a team around the geologist of the University of Oregon, Dylan P. Colón, discovered a previously unrecognized transitional zone that could shed light on how the subsurface magma shoots at the surface. The new research does not tell us when the next eruption could happen, but it's definitely a step in that direction.
At Yellowstone, only a thin layer of crust separates us from boiling evil. Occasionally, this crust is warmed up and softened by the magma so that the lava can rise from a huge furrow, a mantle cloud. In 2014, researchers used seismic waves to detect a large magma body in the upper crust, but with large amounts of carbon dioxide and helium escaping from the ground, scientists found that more magma was lower. This assumption was confirmed in 2015, when researchers who also used seismic waves found a larger magma body at depths of 20 to 45 km.
As important as these findings were, they did not tell the geologist much about the composition, state, and amount of magma that was packed in these bags or how they formed. To fill this gap in our understanding, Colón has developed computer-based data simulations to visualize the processes under Yellowstone. In particular, the researchers wanted to find out where the magma most likely accumulates in the crust.
According to the model – and it is important to remember that it is only a model – opposing geological forces express themselves at depths of three to six miles (five to ten kilometers). This creates a transitional zone where cold, stable rocks give way to hot, partially molten rocks below. This transitional zone, called the "crust of the middle crust", catches the rising magma and causes it to collect and solidify in a large horizontal area. Models suggest that this threshold is about 15 kilometers thick. Fortunately, the simulation fits well with the seismic data collected in 2014 and 2015, suggesting that the models are reasonable approximations to the real world.
The results also show that the threshold consists primarily of rock formed from cooled magma and that the magma bodies exist both above and below it. The above contains gaseous rhyolitic magma that occasionally breaks out to the surface.
The scientists still do not know when the Yellowstone will erupt again, but we now have a better explanation for the magmatic system responsible for these eruptions. In particular, we now know where the eruptible magma comes from and where it gathers. Similar processes can take place elsewhere, and the challenge now is to see how these systems compare. We can not predict eruptions, but advances like this mean we can finally get there.
[Geophysical Research Letters]