1. Department of Geosciences University of Arizona Tucson AZ USA
2. Now at Institute of Geophysical and Planetary Physics Scripps Institution of Oceanography University of California San Diego La Jolla CA USA
3. U.S. Geological Survey Moffett Field CA USA
4. Department of Earth and Planetary Sciences University of California Santa Cruz Santa Cruz CA USA
5. School of Earth and Space Sciences Peking University Beijing China