2025 Academic Thesis Prize : Thomas FRASSON

Thesis Title : Heterogeneous heat flux from mantle convection simulations : impact on the geodynamo and magnetic reversals

His research explores the link between variations in the Earth’s magnetic field and the way heat is transferred between the Earth’s core and mantle.
The magnetic field, generated by the movement of liquid iron in the core, changes in intensity and sometimes reverses over time.

Using advanced numerical models, Thomas Frasson studied how temperature differences at the core–mantle boundary can influence these internal motions and magnetic reversals. He also adjusted these models to account for polar drift, a slow rotation of the mantle that can alter the distribution of hot and cold regions.

His results show that certain thermal configurations, such as a cooler mantle at the equator or a temperature imbalance between the hemispheres, increase the likelihood of magnetic reversals. This work, conducted at thel’Institut des Sciences de la Terre (ISTerre - UGA/CNRS/USMB/IRD/UGE) as part of the Doctoral School : ED STEP - Earth, Environmental and Planetary Sciences, offers new insights into the mechanisms that govern the Earth’s magnetic field, which is essential for protecting the planet and enabling many modern technologies.