Application of the relocation-error distribution on geomagnetic databases. Analyses on the «Historical Italian Geomagnetic Data Catalogue»

L. Casas, A. Incoronato


The reliability of the Historical Italian Geomagnetic Data Catalogue, comprising 536 directions and 393 intensities,
has been assessed by comparing the historical geomagnetic measurements with the GUFM1 model predictions.
Such measurements were assessed at three selected relocation centres. For all the data contained in the
Catalogue it has been calculated the discrepancy between the relocated data and the GUFM1-model prediction
at the relocation centres. There is a correlation between relocation distance and the mean discrepancy. The upper
limit of discrepancy assumable as relocation error has been selected using error distributions previously calculated
using geomagnetic field models. Angular and intensity threshold lines have been slightly shifted upwards
to account for the estimated error of GUFM1 model itself at the considered region, mainly due to the crustal
field. The Italian database proved to contain reliable data, as only a very low percentage of data (namely 14 directions
and 20 intensities) can be considered anomalous. Possible explanations for such questionable data are
suggested. All the remaining data of this catalogue could thus be added to the databases used to produce regional
or global geomagnetic models.


geomagnetism;magnetic dating;relocation

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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X