Geologists used to assume this layer was hard as rock — but it seems to be going soft.
Hell, or something like it, may be a little closer than we thought.
As a new study published in Nature Geoscience reveals, geologists at Cornell and the University of Texas have discovered a "hidden" layer of uber-hot molten rocks just underneath Earth's crust.
"The molten layer is located about 100 miles from the surface and is part of the asthenosphere, which sits under the Earth’s tectonic plates in the upper mantle," a UT press release notes. "The asthenosphere is important for plate tectonics because it forms a relatively soft boundary that lets tectonic plates move through the mantle."
While the asthenosphere was in the past believed to be mostly solid with some liquid here and there to weaken it and make it more flexible, this new discovery suggests that its topmost layer, which was thought to be hard rock, could be softer than scientists once thought.
Article: A partially molten low seismic velocity zone in the asthenosphere is globally prevalent but is not the primary control of the asthenosphere’s low viscosity@JunlinHua @KarenMFischer1 @BrownGeoSci @txgeosciences @CornellEAShttps://t.co/7t1eW5I3oy pic.twitter.com/5iwNRdwPhG
— Nature Geoscience (@NatureGeosci) February 6, 2023
Coincidentally, the idea of studying the asthenosphere came to UT geoscience postdoctoral researcher and primary study author Junlin Hua "while studying seismic images of the mantle beneath Turkey" — which was just the site of a cataclysmic earthquake that's left thousands of people dead — while he was a doctoral student at Brown.
When studying those images, Hua was surprised to discover "signs of partly molten rock under the crust" and, upon compiling other seismic images from around the world until he had a composite map of the asthenosphere, found that the partially-molten rock just below the Earth's crust wasn't anomalous at all, but seemed to be replicated at various points "wherever the asthenosphere was hottest."
"We cannot drill deep down to the asthenosphere," Cornell earth scientist and study co-author Esteban Gazel said in that school's press release, "but we can illuminate that part of the planet using seismic imaging and the chemical compositions of samples that came from the deep Earth, just as a medical doctor would use a sonogram and blood chemistry to determine the condition of a patient."
The asthenosphere's strange characteristics have long puzzled geologists, and with this new discovery of a hidden molten layer that could, the researchers hypothesize, make up half of Earth's entire asthenosphere, we've gotten one step closer to understanding this strange planet of ours.
More on strange geoscience: Earth's Core Appears to Have Stopped Spinning, Scientists Say