Earthquakes paint a picture of the inside of the Earth

(Image: Ebru Bozdağ, University of Nice Sophia Antipolis, and David Pugmire, Oak Ridge National Laboratory)

Eavesdropping on earthquakes is painting a picture of the Earth's interior that looks like the swirling colours inside a marble. This view beneath the Pacific Ocean, based on simulations run by Jeroen Tromp from Princeton University and his team, uses different colours to represent the speed of seismic tremors, giving an insight into the planet's inner structure.

Seismic data allows us to build up a picture of the mantle – the layer between the crust and outer core of the Earth – by following the fate of vibrations created by earthquakes. Since they travel more slowly through viscous materials, such as molten magma, than through solid rock, analysing the seismic fallout from hundreds of earthquakes worldwide reveals inner features like mineral deposits, subterranean lakes and the movement and shape of tectonic plates.

In the image above, slower waves are in red and orange. Faster vibrations, in green and blue, probably correlate with subduction zones, where one tectonic plate burrows under another.

Although this picture focuses on a single region, the researchers are aiming to create a 3D map of the entire mantle, down to a depth of almost 3000 kilometres, by the end of the year.

What makes this kind of analysis possible is the huge number-crunching power of the Titan computer at the Oak Ridge National Laboratory in Tennessee, which can handle 20 quadrillion calculations per second.

So far, Tromp and his colleagues have used their techniques to analyse structures in the mantle beneath California and Europe. Their most recent analysis crunches data from the seismic waves that fanned around the world from a magnitude 7.9 magnitude in China's Sichuan province in 2008.

Journal reference: Journal of Geophysical Research: Solid Earth, DOI: 10.1002/2014JB011638

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

post from sitemap