1. IPGS, CNRS, Univ. of Strasbourg; Strasbourg France
2. Centre for Advanced Study, Norwegian Academy of Science and Letters; Oslo Norway
3. Physics Dep.; Univ. of Oslo; Oslo Norway
4. Géosciences Rennes; Univ. of Rennes 1; Rennes France
5. Det Norske Veritas AS, Research and Innovation; øvik Norway
6. LHYGES, CNRS, Univ. of Strasbourg; Strasbourg France