1. Department of Geology; Southern Illinois University; Carbondale IL USA
2. Department of Geophysics Universidad Complutense de Madrid; Madrid Spain
3. Instituto de Geociencias IGEO (UCM-CSIC), Fac. CC. Físicas; Madrid Spain
4. Institute for Rock Magnetism; University of Minnesota; Minneapolis MN USA
5. Université J. Monnet & UMR6524-CNRS; 42023 Saint-Etienne France