Corne Kreemer, Nevada Geodetic Laboratory, Nevada Bureau of Mines and Geology, University of Nevada, Reno, Reno, NV, United States, Geoffrey Blewitt, Nevada Geodetic Laboratory, Nevada Bureau of Mines and Geology, University of Nevada - Reno, Reno, NV, United States and Paul Davis, University of California, Los Angeles, Department of Earth, Planetary, and Space Sciences, Los Angeles, CA, United States