UCL Earth Sciences


Marisa Wood

“ Using ab-initio methods to investigate Birch’s Law in planetary forming materials. ”

PhD project title:

Birch’s Law: does it work for iron and iron alloys in planetary cores.

Marisa Wood
Project description:

Understanding planetary cores is a challenging task due to their high pressures and temperatures.  One way to investigate materials under these conditions is to use ab-initio calculations and compare them with measurements gained through experimental methods and remote sensing to build up a picture of the interior of terrestrial planets, such as the Earth.

In the Earth’s core the observed shear wave velocity has always been significantly lower than that determined from simulations or experiment.  However, it has been shown that iron exhibits weakening just before melting resulting in a reduction in elastic properties, which may account for this difference.  Prior to this pre-melting region, core materials are thought to obey Birch’s Law, a linear relationship between wave velocity and density.  Wave velocity data is scarce for iron and iron alloys at the conditions of planetary cores.  My PhD uses ab-initio calculations, alongside experimental methods, with the aim of answering whether Birch’s Law can be applied to planetary cores.