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| Focal depths and mechanisms of Tohoku-Oki aftershocks from teleseismic P wave modeling |
| Ling Bai1, Lorena Medina Luna2, Eric A. Hetland2, Jeroen Ritsema2 |
1 Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
2 Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109, USA |
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Abstract Aftershocks of the 2011 Tohoku-Oki great earthquake have a wide range of focal depths and fault plane mechanisms. We constrain the focal depths and focal mechanisms of 69 aftershocks with Mw>5.4 by modeling the waveforms of teleseismic P and its trailing near-surface reflections pP and sP. We find that the ‘‘thrust events’’ are within 10 km from the plate interface. The dip angles of these thrust events increase with depth from ~5° to ~25°. The ‘‘non-thrust events’’ vary from 60 km above to 40 km below the plate interface. Normal and strike-slip events within the overriding plate point to redistribution of stress following the primary great earthquake; however, due to the spatially variable stress change in the Tohoku-Oki earthquake, an understanding of how the mainshock affected the stresses that led to the aftershocks requires accurate knowledge of the aftershock location.
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Received: 11 September 2013
Published: 10 December 2013
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| Fund:the grants of National Natural Science Foundation of China (41274086) to LB and JR, and a University of Michigan Rackham Merit Fellowship to LML |
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Corresponding Authors:
Ling Bai
E-mail: bailing@itpcas.ac.cn
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