1. Norwegian Geotechnical Institute; Sognsveien 72 Oslo 0855 Norway
2. Aarhus Geophysics; ApS. C.F. Møllers Allè 4; Aarhus C DK-8000 Denmark
3. Leibniz Institute for Applied Geophysics; Hannover D-30655 Germany
4. Radic Research; Berlin 13469 Germany
5. Statens vegvesen Region øst; Postboks 1010 Lillehammer 2605 Norway