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Alfred Wegener was a meteorologist and geophysicist who developed continental drift into a coordinated scientific argument. He presented the proposal publicly in 1912 and published its first book-length treatment in 1915. His investigations of the atmosphere grew alongside his polar fieldwork: observations from Greenland expeditions contributed to his work on atmospheric thermodynamics.^[ref]

The matching continental outlines were a starting clue. Alfred Wegener assembled evidence from geophysics, geology and paleontology, including related rock formations and past organisms on opposite sides of the Atlantic. He also used isostasy to challenge the idea that vanished land bridges explained these connections: the density contrast between continents and their substrate mattered to his physical argument. He attempted to test motion through geodesy in Greenland, but the inferred displacement rates were much too large. This distinguishes the broad evidence for continental drift from an individual attempted measurement of it.^[ref]

An geophysicist studies geophysics through mathematical theory, observation or experiment. The field determines the relevant physical systems and measurements, while the individual biographies below connect particular contributions with their scientific ideas.

John Tuzo Wilson introduced transform faults as a distinct type of boundary needed to connect seafloor spreading and other relative plate motions. Where two spreading-ridge segments are offset, active sliding occurs on the connecting part of the fracture; its continuation beyond a ridge can separate crust moving together and need not remain an active plate boundary. The geometry predicts a slip direction that cannot be inferred merely by treating the offset ridge as a formerly continuous line. His 1965 proposal made a structural pattern into a test of plate tectonics.^[ref]

A geophysicist associated with transform faults and the Wilson cycle.

Paul Spudich coauthored a description of rupture directivity based on arrival-time contours across a finite earthquake source. If a rupture advances toward a receiver, seismic waves from successively rupturing patches can arrive over a compressed interval; retreating rupture spreads those arrivals out. The formulation makes this directional pulse concentration depend on source geometry and rupture timing, supplying a physical measure for interpreting strong ground motion.^[ref]

Geophysicist and author of primary studies of earthquake ground motion and rupture directivity. His authorship and USGS affiliation are documented on the 2004 report: pubs.usgs.gov/of/2004/1268/ .