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 (M-w 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 similar to 30-70 s and maximum slip of similar to 60 m. Down-dip slip spreads over a wider area with smaller maximum slip (