We will conduct a geophysical survey of the Thwaites Glacier, Antarctica during the 2019-2020 and 2020-2021 Antarctica field season to constrain physical processes that enable fast glacier motion. We will conduct radar, active source seismic, and passive source seismic surveys. A proposal will be submitted to NSF PROGRAM SOLICITATION 17-505 "Thwaites: The Future of Thwaites Glacier and its Contribution to Sea-level Rise" on MARCH 1, 2017. A letter of support is requested.