1. Institute of Geological Sciences, Universität Bern, Baltzerstrasse 1+3, CH-3012 Bern, Switzerland
2. Department of Physics, Faculty of Science, University of Zagreb, 10040 Zagreb, Croatia
3. Department of Computer Science, University of Idaho, Moscow, ID 83844, USA
4. Earth and Planets Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road NW, Washington, DC 20015, USA