1. Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA.
2. Department of Geology and Geophysics, Yale University, New Haven, CT, USA.
3. Department of Geological and Mining Engineering and Sciences, Michigan Technological University, Houghton, MI, USA.
4. Department of Physics, Harvard University, Cambridge, MA, USA.
5. Department of Earth and Planetary Sciences, University of California Berkeley, Berkeley, CA, USA.