1. Department of Earth and Planetary Sciences Harvard University Cambridge MA USA
2. Now at Fluid Dynamics and Solid Mechanics Group Los Alamos National Laboratory Los Alamos NM USA
3. Department of Geosciences University of Arizona Tucson AZ USA
4. Now at Department of Earth, Atmospheric and Planetary Sciences Massachusetts Institute of Technology Cambridge MA USA
5. Lamont‐Doherty Earth Observatory Columbia University Palisades NY USA
6. Research School of Earth Sciences Australian National University Canberra ACT Australia