Modelo arqueomagnético global para la Anomalía de la Edad de Hierro de Levante

Resumen

The LIAA (“Levantine Iron Age Anomaly”) is a short-decadal geomagnetic field variation found by Shaar et al. (2016, 2017) in the Levantine Region and characterized by high intensities with virtual axial dipole moments around 160 ZAm2. It’s been recorded by archaeomagnetic data coming from Eastern Europe and Western Asia constraining the LIAA between 1050 BC and 700 BC. Geometrically speaking, the LIAA can be related to a big geomagnetic positive anomaly (spike) at the Earth’s surface. Davies and Constable (2017) indicated that this anomaly is characterized by small spatial wavelengths and thus it is due to the contribution of high spherical harmonic degrees. Following this work, we try to analyse the LIAA from a realistic model of the archaeomagnetic field, using the most recent archeomagnetic dataset covering the spatial and temporal period of the LIAA. To reconstruct the spike event, we develop a spherical harmonic global model as a perturbation of the Gauss coeffi- cients from a previous paleomagnetic global model that did not use the LIAA data record. Our results show that the LIAA event could be characterized by larger spatial wavelengths and thus it is defined by lower harmonic degrees (between 3 and 6) than expected by the previous work.