[1] Univ Calif Berkeley, Dept Earth & Planetary Sci, Berkeley, CA 94720 USA
[2] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[3] Univ Calif Berkeley, Miller Inst Basic Res Sci, Berkeley, CA 94720 USA
[4] Lawrence Livermore Natl Lab, Shock Phys Grp, Livermore, CA 94550 USA
[5] Carnegie Inst Sci, Geophys Lab, Washington, DC 20015 USA
[6] Howard Univ, Washington, DC 20059 USA