Título:  “Reconstructing Earth’s magnetic past with Micromagnetic Tomography”

Expositor: Dr. Lennart V. de Groot, Associate Professor at Paleomagnetic Laboratory Fort Hoofddijk, Department of Earth Sciences, Faculty of Geosciences, Utrecht University, the Netherlands.

Abstract:

The Earth’s magnetic field protects our planet from harmful electromagnetically charged particles from the Sun that could otherwise strip away our atmosphere and interfere with our modern technology. This field is generated by vigorous convection in the liquid outer core, a highly dynamic process that results in temporal variations and regional anomalies, such as the ongoing South Atlantic Anomaly.

 To reconstruct past variations of the Earth’s magnetic field and improve our understanding of its behavior, we analyze magnetic signals stored in volcanic rocks. When lava cools, iron-bearing minerals become magnetized in alignment with the prevailing geomagnetic field, preserving a record of its past state. Volcanic regions with frequent eruptions thus serve as natural archives of geomagnetic history. However, traditional methods to reconstruct the past intensity of the field, which measure bulk samples containing millions of iron-bearing minerals simultaneously, have a low success rate—only 10–20% of lavas yield reliable paleomagnetic data.

Emerging micromagnetic imaging techniques now allow for the direct measurement of magnetic moments arising from individual iron-bearing minerals, enabling selective interpretation of only the most reliable signals. Building on these advancements, we have developed Micromagnetic Tomography, a novel approach that enhances our ability to extract high-fidelity paleomagnetic information. This breakthrough opens new possibilities for understanding the evolution of Earth’s magnetic field with unprecedented precision.