Inversion of high-rate (1 sps) GPS data for rupture process of the 11 March 2011 Tohoku earthquake (Mw 9.1)

The space‐time fault displacement history of the 11 March 2011 Tohoku (Mw 9.1) megathrust earthquake is obtained by least‐squares inversion of high‐rate (1 sample per second) GPS ground motions recorded in Japan. Complete near‐source time‐varying and static ground motions for periods ≥25 s are fit in the inversion using a normal mode formalism to compute the Green functions. The basic rupture pattern is stable for various choices of model parameters and solution smoothing, and excellent fits to the complete seismo‐geodetic ground motions are obtained. The preferred solution has concentrations of slip near the trench and hypocenter, with sub‐fault source time function durations of ∼30–70 s and maximum slip of ∼60 m. Down‐dip slip spreads over a wider area with smaller maximum slip (