Why Seismic Waves Spontaneously Race Inside the Earth

(ETH Zurich, June 06, 2025)

Researchers at ETH Zurich, led by Prof. Motohiko Murakami, have discovered that solid rock flows nearly 3000 kilometers below the Earth's surface, overturning previous beliefs about the Earth's interior. This flow occurs in the so-called D'' layer, where earthquake waves speed up due to solid rock aligning its crystals under extreme conditions. This finding not only solves the D'' layer mystery but also sheds light on deep Earth dynamics, establishing the concept of solid rock flow. The team used laboratory experiments and computer simulations to uncover this. They measured seismic wave speeds at high pressures and temperatures mimicking the D'' layer's environment. By combining these measurements with computer models that simulate crystal orientations, they provided a detailed view of Earth's inner workings. This research offers insights into volcanic and tectonic activities and may affect our understanding of the Earth's magnetic field, marking a significant advancement in geological science.