Beneath Earth s surface, nearly 3,000 kilometers down, lies a mysterious layer where seismic waves speed up inexplicably. For decades, scientists puzzled over this D” layer. Now, groundbreaking experiments by ETH Zurich have finally revealed that solid rock flows at extreme depths, acting like liquid in motion. This horizontal mantle flow aligns mineral crystals called post-perovskite in a single direction, explaining the seismic behavior. It s a stunning leap in understanding Earth s deep inner mechanics, transforming a long-standing mystery into a vivid map of subterranean currents that power volcanoes, earthquakes, and even the magnetic field.
