Geoffrey Blewitt

Biosketch

Geoffrey Blewitt, PhD is a professor at the University of Nevada, Reno, USA, at both the Nevada Bureau of Mines and Geology, and the Department of Physics. He earned his BSc in Physics from Queen Mary College, University of London and his PhD in Physics from Caltech, where he was a member of the IMB collaboration that discovered the neutrino burst from Supernova 1987A. His career started at the NASA Jet Propulsion Laboratory, as a leading developer of the GIPSY-OASIS software for millimeter-precise positioning with GPS data using patented techniques. He founded and now runs the Nevada Geodetic Laboratory which processes data from all available geodetic GPS data in the world acquired since 1994, currently from over 22,000 stations. Dr. Blewitt’s research contributions earned him the Vening Meinesz Medal from the European Geosciences Union, and multiple NASA awards. He is a Fellow of the American Geophysical Union, a Fellow of the International Association of Geodesy, and he is a member of the NAS. Dr. Blewitt has served as President of International Association of Geodesy Commission 1 on Reference Frames, as President of the American Geophysical Union Geodesy Section, and as a member of two U.S. National Academies Committees on precise geodetic infrastructure. In 2023, he was honored to be invited as Union Lecturer at the quadrennial assembly of the International Union of Geodesy and Geophysics in Berlin, where he gave the presentation “Geodesy, It’s about Time.”

Research Interests

Dr. Blewitt’s research spans two vastly different scientific areas: one on geodesy and geophysics, the other on the search for dark matter and multi-messenger astrophysics. In the first scientific area, topics of interest include improving satellite geodetic techniques such as high precision GPS, global reference frames, and the application of satellite geodesy to geophysics including plate tectonics, earthquake cycle, surface mass loading, glacial isostatic adjustment, sea-level change, and atmospheric science. A recurring theme in his analysis of GPS network displacements is the use of robust statistics. In the second scientific area, Dr. Blewitt uses atomic clock data of the GPS satellites to search for new exotic physics, including galactic dark matter and low-mass fields emanating from black hole merger events. Both areas of research require exquisite modeling and parameter estimation techniques of processes affecting to the GPS carrier phase observable, including celestial mechanics of the GPS satellite orbits, the relativistic propagation of GPS signals and the impact of the atmosphere, changes in the shape of the Earth and Earth surface deformation due to tidal and non-tidal effects, and instrumental biases. Residual signals not explained by known models are then probed as to their hypothetical origin, where they be caused by redistribution of water on or near the Earth’s surface, earthquakes, mantle dynamics, atmospheric water vapor variation, or dark matter affecting atomic clock frequency.