Near Surface Conductive Zones in Hessdalen Valley (Norway) Inferred by Preliminary VLF Surveys

During the last four years VLF surveys have been performed in Hessdalen valley during four wide geophysical field campaigns including Total Magnetic Field surveys, time recordings of the electrical field, and magnetotelluric soundings. VLF measurements have been carried out on a 20 m average spacing along a large number of traces totaling 70 km length. The covered area is now about 100 km2. Hereafter, we focus on the results of the VLF upshots. A part of the conductive zones have been found to be related with mineral deposits (mainly sulphites). The distribution of these conductive zones could suggest that they draw an ellipse of 6x12 km dimensions related with the anticline in the area. These results combined with the other geophysical results will contribute to understand if and how these, very superficial, structure could participate to the genesis of the so-called Hessdalen lights.