Ke Gao, Los Alamos National Laboratory, Los Alamos, NM, United States, Esteban Rougier, Los Alamos National Laboratory, EES-17, Los Alamos, NM, United States, Robert A Guyer, University of Nevada Reno, Physics Department, Reno, NV, United States and Paul A Johnson, Los Alamos National Laboratory, Earth and Environmental Sciences: Geophysics (EES-17), Los Alamos, NM, United States