1. Department of Earth, Ocean and Atmospheric Sciences; University of British Columbia; Vancouver British Columbia Canada
2. Department of Earth Sciences; University of Toronto; Toronto Ontario Canada
3. Department of Physics; University of Toronto; Toronto Ontario Canada
4. Department of Earth and Planetary Science; The Johns Hopkins University; Baltimore Maryland USA
5. Gedex Systems Inc.; Mississauga Ontario Canada
6. NASA Goddard Space Flight Center; Greenbelt Maryland USA
7. Department of Earth Science; Rice University; Houston Texas USA