Sunyoung Park, California Institute of Technology, Seismological Laboratory, Pasadena, MA, United States, Victor C Tsai, California Institute of Technology, Seismological Laboratory, Pasadena, CA, United States; Brown University, Department of Earth, Environmental and Planetary Sciences, Providence, RI, United States and Miaki Ishii, Harvard University, Earth and Planetary Sciences Department, Cambridge, MA, United States