Centre of the Earth revealed

15 December 2005

Findings published today in Nature help explain a region deep in the Earth's interior that has puzzled scientists for decades.

This knowledge will aid scientists trying to explain the huge forces in the Earth's mantle which build, shake and eventually destroy the surface on which we live.

Scientists from the Universities of Bristol, Leeds and University College London have collaborated to explore the seismic properties of a new mineral and show how it can explain images of the interior that have hitherto been so enigmatic.

At a depth of nearly 3000 km below the surface lies a boundary that separates the rocky part of the Earth (the mantle) from its iron core. This boundary is the last stop for material that has descended into the mantle from the thin layer of crust that we live on. Below the mantle lies circulating liquid iron, which is responsible for the generation of the Earth's magnetic field.

For decades scientists have struggled to understand the properties and behaviour of this region as it could provide insights into the long-term evolution of our planet.

Professor Mike Kendal from Bristol University explained, "Because the pressures and temperatures of the Earth's interior are so great, one of the best ways of imaging the Earth's interior is by using seismic waves generated by large earthquakes - in much the same way as ultrasound is used to image the body's interior. But in the past it has been very difficult to interpret these images due to our lack of knowledge about the materials that make up the deep Earth."

Using methods borrowed from quantum physics, the team recently developed new theoretical techniques for synthesizing what rocks will look like at very high pressures and temperatures. They have used these techniques to study a recently discovered mineral phase at the base of the mantle, which may explain many of the mysteries of this region.

Professor David Price from University College London said, "Understanding the properties of this new mineral will allow better interpretations of what happens when cold material thrust into the Earth pools at the base of the mantle in continental-scale regions - such as happens below areas like Sumatra and Japan - and how hot upwellings, originating from the boundary between the iron core and the mantle, feed volcanoes such as those on Hawaii and Iceland."

Further information

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Notes

1. The collaboration is a result of one of the first research consortiums funded by the Natural Environmental Research Council. The £320,000 grant will increase knowledge of the Earth's interior, a key part of the Earth system. The Natural Environment Research Council is one of the UK's research councils. It uses a budget of about £350m a year to fund and carry out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists. It is addressing some of the key questions facing mankind, such as global warming, renewable energy and sustainable economic development.

2. The paper, 'Efficacy of the post-perovskite phase as an explanation for lowermost-mantle seismic properties', is published in Nature, 15 December.

The authors:

Dr James Wookey, NERC research fellow, University of Bristol (Department of Earth Sciences) j.wookey@bristol.ac.uk
Dr Stephen Stackhouse, postdoctoral research associate, University College London (Department of Earth Sciences)
Prof Michael Kendall, University of Bristol (Department of Earth Sciences) gljmk@bristol.ac.uk
Prof John Brodholt, University College London (Department of Earth Sciences) j.brodholt@ucl.ac.uk
Prof David Price, University College London (Department of Earth Sciences)

Press release: 60/05

Centre of the Earth revealed

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