1. Department of Geology University of Cincinnati Cincinnati OH 45221 USA
2. GFZ German Research Centre for Geosciences Telegrafenberg 14473 Potsdam Germany
3. Department of Marine, Earth, and Atmospheric Sciences North Carolina State University Raleigh NC 27695 USA
4. Department of Earth, Planetary, and Space Sciences University of California Los Angeles CA 90095 USA
5. Department of Physics Purdue University West Lafayette IN 47907 USA
6. Department of Earth, Atmospheric and Planetary Sciences Purdue University West Lafayette IN 47907 USA