Mysterious 'Donut' Structure Found Hidden Inside Earth's Core
About 2,890 kilometres beneath our feet lies a gigantic ball of liquid metal: our planet's core. Scientists like me use the seismic waves created by earthquakes as a kind of ultrasound to "see" the shape and structure of the core.
Using a new way of studying these waves, my colleague Xiaolong Ma and I have made a surprising discovery: there is a large donut-shaped region of the core around the Equator, a few hundred kilometres thick, where seismic waves travel about 2% slower than in the rest of the core.
We think this region contains more lighter elements such as silicon and oxygen, and may play a crucial role in the vast currents of liquid metal running through the core that generate Earth's magnetic field. Our results are published today in Science Advances.
Most studies of the seismic waves created by earthquakes look at the big, initial wavefronts that travel around the world in the hour or so after the quake.
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