Scientists Found 6 Weird Structures in Earth’s Center. They Could Wreak Havoc on Its Surface.

4 min readHere’s what you’ll learn when you read this story:The core-mantle boundary (CMB) is where Earth’s lower mantle meets its (almost) liquid core. Until now, scientists have detected mostly larger seismic waves in that area.After a team of researchers trained an AI algorithm to sift through data and find faint seismic signals known as PKP precursors, the team found six previously unknown irregularities.Because these deep irregularities scatter PKP precursors, which appear ahead of more intense waveforms, knowing where they are located can help with extreme weather forecasts.Predicting phenomena like earthquakes and volcanic eruptions requires having at least some idea of what’s going on at the interface between Earth’s solid mantle and its mostly iron core, which is extremely viscous but not completely solid. Here, some 1,800 miles (2,900 km) beneath the surface, massive amounts of heat and material are transferred between the two layers. Though much about these deep processes remains unknown, there are certain seismic waves whose trajectories can indicate irregularities near the literal center of the Earth as they are scattered and deflected.The seismic waves in question are known as PKP precursors, and are thought to propagate in thin mantle layers known as “ultra-low velocity zones.” These layers are notorious for slowing down seismic activity, leading to the accumulation of PKP precursors that may trigger mantle plumes, which often surface as volcanic eruptions—think Yellowstone’s famous geysers, or the lava flows in the Hawaiian islands. Unfortunately, the issue with these precursor signals (which often precede more powerful seismic waves called PKIKP) is that they have often been too faint to detect.To try and solve this problem, a team of researchers decided to train an AI algorithm to scan more than 2 million earthquake recordings that were taken on every part of the planet from 1900 to 2024. The algorithm found 175,000 PKP precursors that led to six previously unknown irregularities.Earth is dynamic. As its innards continually evolve at the core-mantle boundary (CMB)—and, right above that, the deepest layer of the lower mantle—they influence mantle plumes, subduction of tectonic plates that can cause earthquakes, tsunamis, volcanism, and the constant influx and outflow of material between the core and mantle. The irregularities in that part of the CMB that have traditionally been observable to scientists are enormous, but finding out more about fainter signals can help us understand the mineralogical properties and changing processes of these regions. The focus on PKP precursors comes from the unique paths they travel and their tendency to be highly sensitive to irregularities on a smaller scale.In doing an analysis like this, one needs to be able to filter out significant noise in the data being sorted through. And while there have been some techniques used to correct for noise obscuring these barely detectable signals in the pasr, scientists hunting these signals down have experienced significant limitations that AI can now expand on.“Machine-learning-based automatic detection of seismic phases offers a promising avenue for addressing the underutilization of available data, and has been successfully demonstrated for a variety of phases,” the researchers said in a study recently published in Journal of Geophysical Research: Solid Earth. “By contrast, the identification of PKP precursors has long relied on manual, [individual] screening [every time they occur].”In order to identify the PKP precursors and the irregular structures off of which they could be bouncing—some of which could could take the form of blobs formed from fragments of subducting tectonic plates, which break and melt partially when they sink into scorching magma—the team of researchers gathered data from the International Federation of Digital Seismograph Networks (and other sources), and used three deep-learning models to train an algorithm to evaluate data and single out PKP precursors. Then, they mapped the irregularities the models found, and discovered that the algorithm had identified 175,000 PKP precursor signals that would have been too faint to detect otherwise.These findings suggest the presence of irregularities all over the Earth—a stretch of land that extends from the northwestern Iberian Peninsula through Central Europe, the higher latitudes of Northern Eurasia, the Trans-Pacific Belt that reaches from the Northwest Pacific to Alaska, an area that spans Southern Africa and the Mozambique Channel, the southeastern South Atlantic Ocean Basin, and along the Antarctic continental shelf—that had previously been missed entirely.Locating and mapping these structures has shown that irregularities at the CMB may be much more expansive than scientists once assumed. It can also make extreme weather predictions more accurate, especially since the scattering of PKP precursors that run into irregular structures could determine the spread of tectonic activity such as terrestrial earthquakes, underwater earthquakes from which tsunamis arise, and the intensity of volcanic eruptions.“We not only independently verified multiple scattering regions associated with…deep anomalies, but also identified six new high-potential scattering targets,” the researchers concluded. “Within [our] interpretive limits, these small-scale structures may be related to remnants of multi-episode subjected slabs, partial melting, mineral phase transition effects, and other related processes.”Elizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.