1. Institut für Geophysik; University of Münster; Münster Germany
2. Department of Geology and Petroleum Geology; School of Geosciences, University of Aberdeen; Aberdeen UK
3. Department of Geological Engineering and Sciences; Michigan Technological University; Houghton Michigan USA
4. U.S. Geological Survey; Vancouver Washington USA
5. Institut für Mineralogie; University of Münster; Münster Germany