The team focused on shear waves generated by earthquakes, which travel through the mantle, pass into the core, and return. These waves behave differently depending on the internal structure of the material they cross. This phenomenon, known as seismic anisotropy, reveals where rock has been deformed.<\/p>\n
Using this method, scientists mapped nearly 75% of the mantle just above the core, identifying anisotropy in about two-thirds of the regions studied.<\/p>\n
![\"Seismic](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/04\/Seismic-observations-of-Earths-deep-mantle-1200x1181.jpg.webp.webp\")
Seismic observations of Earth\u2019s deep mantle. Credit:The Seismic Record<\/p>\n
Subducted Slabs Are Driving Massive Deformation<\/p>\n
One of the clearest patterns to emerge is the concentration of deformation in areas where ancient tectonic slabs<\/a> have accumulated. These slabs, once part of Earth\u2019s surface, were pushed downward through subduction and now rest deep in the mantle.<\/p>\n According to The Seismic Record<\/a>, the presence of anisotropy aligns closely with these regions. This supports earlier predictions from geodynamic simulations, though such a global confirmation had not been achieved with seismic data<\/a> until now.<\/p>\n \u201cThis isn\u2019t that surprising in a sense, because that is predicted by geodynamic simulations,\u201d Wolf said. \u201cBut at the scale that we\u2019re looking at, it\u2019s not really been shown using those methods that we\u2019re using.\u201d<\/p>\n Mantle Materials Under Extreme Stress<\/p>\n At depths approaching 2,900 kilometers, pressure and temperature reach extreme levels. These conditions can alter the internal structure of minerals, creating new forms of anisotropy. Based on the researchers\u2019 findings, this may explain much of the deformation detected near the core. Wolf noted that:<\/p>\n \u201cWe know that deformation in the upper mantle is dominated by the drag of the plates that move across it. And that extremely well approximates what we know from seismic anisotropy about the deformation of the upper mantle.\u201d He added: \u201cbut we don\u2019t have any of this kind of large-scale understanding for flow in the lowermost mantle. And that\u2019s really what we want to get at.\u201d<\/p>\n Some slabs might also retain older structural signatures formed when they were closer to the surface. Still, the study suggests that active deformation near the core-mantle boundary is the more likely explanation in many cases. Not all regions showed clear signals of anisotropy. The researchers caution that this does not indicate an a bsence of deformation, but rather limits in current detection methods.<\/p>\n![\"Global](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/04\/Global-distribution-and-interpretation-of-seismic-anisotropy-in-Earths-lowermost-mantle-scaled.png.w.webp\")
Global distribution and interpretation of seismic anisotropy in Earth\u2019s lowermost mantle. Credit: The Seismic Record<\/p>\n