Seminar by Marina Puente Borque (Complutense University of Madrid) – “Windows into the ancient geomagnetic field: Millennial-scale variability and core dynamics”

Satellite constellations and observatory networks enable for near–real-time monitoring of the evolution of the Earth’s magnetic field. However, the characteristic timescales of the geomagnetic field extend far beyond the period covered by instrumental observations. To reconstruct its past behaviour, we therefore rely on indirect records such as natural signals preserved in volcanic lava flows, sedimentary sequences, and even archaeological materials. Geomagnetic variations span timescales from millions of years to just a few years. Studying millennial-scale changes through archaeomagnetic models provides key insights into core dynamics, as well as practical applications such as the dating of archaeological sites. In this talk, I will discuss what recent archaeomagnetic reconstructions reveal about the geomagnetic field over the past 5000 years, intensity anomalies, rapid changes in secular variation, as well as the link to variations in the length of day.