| 1978 | Postdoctoral Research Associate, Scripps Institution of Oceanography, San Diego |
| 1978-1979 | Visiting Assistant Professor, University of Minnesota, Minneapolis |
| 1979-1982 | Geophysicist, Branch of Tectonophysics, Office of Earthquake Studies, U.S. Geological Survey, Menlo Park, California |
| 1982-1986 | Assistant Professor of Geophysics, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA |
| 1986 | Associate Professor of Geophysics, EAPS, MIT, Cambridge, MA |
| 1989-1998 | Professor of Geophysics, EAPS, MIT, Cambridge, MA |
| 1993-1995 | Associate Director, MIT SeaGrant College Program, Cambridge, MA |
| 1995-1997 | Director, MIT/WHOI Joint Program in Oceanography and Applied Ocean Science and Engineering, Cambridge, MA |
| 1997-2009 | President; Chief Executive Officer, Monterey Bay Aquarium Research Institute, Menterey, CA |
| 1998-2009 | Professor, Department of Earth Science, UC Santa Cruz |
| Professor of Geophysics, Stanford University, Stanford, CA |
| 2009-2013 | Director, US Geological Survey, Reston Virginia |
| 2013-2013 | Visiting Research Scientist, Scripps Institution of Oceanography/IGPP, San Diego |
| 2013-2016 | Editor-in-Chief, Science, American Association for the Advancement of Science, Washington, D.C. |
| since 2015 | Professor, Georgetown University, Washington, DC. |
| since 2016 | President, National Academy of Sciences, Washington, D.C. |
