Hooray, there’s a new study on the Yellowstone supervolcano out! No, it’s not about to erupt, nor is it now any more or less dangerous than we thought. Just thought we’d clear that up right at the beginning.
So what’s this one all about? Well, it’s a supercomputer simulation of the engine beneath Yellowstone, which aims to clarify a few details about its current state and its evolution over the last few million years. As it so happens, their conclusions provide fresh insight into how the infamous caldera's underlying magmatic system came to be.
Thanks to the incredible work of interdisciplinary scientists, we've come to know a fair bit about Yellowstone in the last few decades. For example, we know, through the use of ground-penetrating seismic waves, that its magma chamber has a shallower, more viscous, rhyolitic upper section, and a far more voluminous basaltic lower section. (Both, incidentally, are mostly solid, which is one of the reasons we aren't expecting any sort of eruption anytime soon.)
That’s where our supercomputer simulation comes in. The authors used it to focus on “how the observed structure of Yellowstone's current magmatic system – that of a 2-layer complex – came to be,” Dr Michael Poland, the Scientist-in-Chief at Yellowstone Volcano Observatory – who wasn’t involved in the study – told IFLScience.
Geophysical data indicates that the upper chamber is found between 5 and 17 kilometers (3.1 to 10.6 miles), and the more massive lower chamber is found between 20 and 50 kilometers (12.4 and 31.1 miles) below. The new paper has no issue with that – but wait, there’s more!
Between the more brittle upper crust and its more ductile underbelly, molten material is thought to get bunched up and accumulate. The University of Oregon and ETH Zurich team suggests that, thanks to this boundary, a huge, horizontal magmatic body named a sill – like window sill – has formed, between 10 and 25 kilometers (6.2 and 15.5 miles).
The study suggests that this sill not only provided heat to melt the surrounding crust, but it has also cooled and solidified over time. This creates a dividing line that “separates the partially molten crust above and below it into the two magmatic systems seen in the geophysical images.”
Rather wonderfully, this Geophysical Research Letters paper’s findings help to provide the "why", the reasoning, to match what we've seen through geophysical research.
As it so happens, the system is also fueled by a mantle plume. This superheated, solid fountain rises to somewhat shallow depths, where it decompresses, melts, and adds magma to the plumbing system. A study published in March revealed, through geophysical imaging techniques, that the plume stretches from Yellowstone National Park all the way to Mexico.
This new study also briefly zeroes in on the plume's apex, which the authors suspect is about 175°C (347°F) hotter than the surrounding mantle. That’s all well and good, but this research doesn’t change our overall understanding of that underlying plume.
The paper’s “just looking at the shallowest expression of the plume, and this has no real bearing on the plume existence itself,” Poland said, adding that it’s nevertheless “quite neat what these various studies are revealing about the subsurface, and how it came to be that way.”
Essentially, this paper’s not a revelation, nor does it make anything more mysterious. It’s a fine study that pairs nicely with pre-existing research, like a complimentary botanical being added to a tasty gin.