UCL News


Journey to the centre of the Earth guided by seismic waves

31 August 2005

The centre of the Earth is a place where man can only make hypotheses - important hypotheses, for example to try to understand earthquakes, volcanic eruptions, the drift of continents and the Earth's magnetic field.

From the analysis of seismic waves, which vary depending on the material in which they travel, seismologists have … deduced that the core of the Earth, mainly formed by iron, must also contains small quantities of other elements.

The latest information on the temperature and composition of the Earth's core are from [Dr] Dario Alfé [UCL Earth Sciences]. For his scientific merits, Alfé has just received the European Young Investigator Award, with a value of €1.25 million. …

"Using the Car-Parrinello method, we deduced," Alfé explains, "that the temperature of the nucleus is 5,500K (similar to that of the surface of the sun) ... and that there is oxygen in the liquid part of the core. The oxygen rises to the surface, like the bubbles in soft drinks, because is lighter than the rest of the liquid, and in doing so it generates motions in the liquid that produce electric currents, responsible for the generation of the Earth's magnetic field. This information is fundamental for the construction of a model which allows predictions on the phenomena generated by the core."

'Il Sole 24 Ore', Italy