The relationship of velocity structure, slip distribution and aftershock in the hypocenter area of the 11 March 2011 Tohoku earthquake

Understanding the relationship between velocity structure, slip distribution and aftershock in the fault plane of a great earthquake could provide significant insights into the rupture process of the earthquake. In this presentation, we determine slip distribution, aftershock location and velocity structure of the fault plane in the area near the hypocenter of the 11 March 2011 Mw 9.0 Tohoku earthquake, occurring on the megathrust off the Pacific coast. We invert slip distribution using a finite fault inversion technique, which uses both body waves and long period seismic waves recorded in teleseismic distances based on a simulated annealing algorithm in the wavelet domain. We relocate the aftershocks and determine their relative origin times in high precision based on the observed relative travel times of P waves between the events. And, we image the velocity structure in the hypocenter area using the Virtual Seismometer method. In this method, we reconstruct the Green's function between aftershocks using source-receiver reciprocity and seismic interferometry. We then use the derived Green's functions to invert high-resolution velocity structure in the fault plane. We will discuss the relationship between these parameters and implication of these results to the rupture process of the Tohoku earthquake.