Structural heterogeneity in the megathrust zone and mechanism of the 2011 Tohoku-oki earthquake (Mw 9.0)

Creators: Zhao, Dapeng; Huang, Zhouchuan; Umino, Norihito; Hasegawa, Akira; Kanamori, Hiroo

Abstract

The great 2011 Tohoku-oki earthquake (Mw 9.0) and its 339 foreshocks and 5,609 aftershocks (9–27 March 2011) were relocated using a three-dimensional seismic velocity model and local P and S wave arrival times. The distribution of relocated hypocenters was compared with a tomographic image of the Northeast Japan forearc. The comparison indicates that the rupture nucleation of the largest events in the Tohoku-oki sequence, including the mainshock, was controlled by structural heterogeneities in the megathrust zone.

Additional Information

© 2011 American Geophysical Union. Received 7 June 2011; accepted 6 August 2011; published 7 September 2011. We thank the data center of the JMA Unified Catalogue for providing the high‐quality arrival‐time and waveform data used in this study. This work was partially supported by the Global‐COE program of Earth and Planetary Sciences, Tohoku University, and a research grant from Japan Society for the Promotion of Science to D. Zhao. The figures were made by using GMT [Wessel and Smith, 1998]. T. Iinuma kindly provided Figure 3b. We are grateful to K. Koper, T. Lay, D. Wiens and F. Pirajno for helpful discussions. M. Wysession (the editor) and two anonymous referees provided constructive review comments that improved the paper. The Editor wishes to thank two anonymous reviewers for their assistance evaluating this paper.

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