Filling Critical Archeomagnetic Data Gaps

Strong changes of the geomagnetic field intensity on decadal to centennial timescales originating from the Earth’s outer core are of crucial importance for infrastructures and living organisms because they affect the shielding strength against energetic cosmic particles. Within the FWF project “Filling critical archeomagnetic data gaps” (P 36496), two periods characterized by extraordinarily strong field intensity variations will be investigated with new records from Central Europe.

The time intervals of interest comprise the Bronze to Iron Age transition and the Early Medieval Ages, for which extremely high field intensities, most likely caused by geomagnetic non-dipole features, have been reported within the Levantine region and Western Europe, respectively. Despite their importance for understanding the recent evolution of the Earth’s field and the underlying outer core dynamics, these events are poorly characterized, due to the temporal and spatial scarcity of reliable records.The main goal of the project is to fill large gaps associated with these periods in current archeomagnetic databases, through the measurement of archeological materials from strategically chosen locations. These materials mainly comprise potsherds from about 30 different sites in Austria, Bosnia, Serbia, Slovenia, Germany, Poland, and Sweden. In case of promising new excavations, additional in-situ sampling campaigns will be conducted. State-of-the-art rock magnetic and archeomagnetic methods will be applied to obtain high-quality records. Advanced archeointensity protocols, along with vital corrections and quality checks, will be used. Furthermore, different materials from the same sites will be examined and possible contradictions due to differing heating conditions and material properties evaluated in order to scrutinize the validity of field intensity estimates.The newly gained records will significantly improve the spatio-temporal data coverage for the periods of interest, enabling a detailed reconstruction of the related strong and rapid geomagnetic field variations. This will lead to the improvement of an existing Bayesian modelling approach which enables the incorporation of extremely heterogeneous data, providing adequate modelling uncertainty assessment. The updated archeomagnetic field model will provide a better description of the field evolution during these interesting geomagnetic events as well as valuable boundary conditions for associated geodynamo processes. Moreover, the potential of archeomagnetic dating will be significantly enhanced in the study areas.