1. Department of Mechanical and Civil Engineering, California Institute of Technology, Pasadena, California, U.S.A.
2. Incorporated Research Institutions for Seismology, Washington, D.C., U.S.A.
3. Department of Geology and Geophysics, Yale University, New Haven, Connecticut, U.S.A.
4. Department of Geosciences, Princeton University, Princeton, New Jersey, U.S.A.
5. Geology Department, Western Washington University, Bellingham, Washington, U.S.A.
6. Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, U.S.A.
7. Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, UC San Diego, La Jolla, California, U.S.A.
8. College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, U.S.A.
9. Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, California, U.S.A.