The Interpretation of Aeromagnetic Survey in Eurajoensalmi, Olkiluoto, Finland (2008)

In 2001, Olkiluoto was selected as the site for the final disposal of spent nuclear waste in Finland. In April 2008, a high resolution aeromagnetic survey was carried out in the Eurajoensalmi inlet in order to investigate the sea and coastal areas north and west of Eurajoensalmi. The main objective of the study was to improve the magnetic image of Eurajoensalmi area, to locate the area’s most significant magnetic features, and by magnetic modelling, find the best geological explanations for them. Survey was conducted by Geological Survey of Finland and ordered by Posiva Oy. In order to fully interpret the magnetic data, various derivatives and visualisation techniques were used in addition to total magnetic field. In total four areas were modelled. Modelling was intentionally kept relatively simple using as large and continuous bodies as possible. Modelled areas demonstrate that magnetic modelling is a very suitable method for defining the properties of concealed structures causing magnetic anomalies and most importantly for finding reasonable geological explanations for them. A new airborne magnetic survey has been planned for the year 2009 to expand the survey area to the south.