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Earth, Planets and Space
Fig. 1 | Earth, Planets and Space

Fig. 1

From: Normal-faulting stress state associated with low differential stress in an overriding plate in northeast Japan prior to the 2011 Mw 9.0 Tohoku earthquake

Fig. 1

Lower-hemisphere, equal-area stereographic focal mechanism solutions of earthquakes prior to the 2011 Tohoku earthquake (from Imanishi et al. 2012). Colors of focal spheres indicate depths of hypocenters. Numbered focal mechanisms corresponding to solid circles are those used in this study; seismic events plotted with open circles were not used. The focal mechanism for the 2011 Iwaki earthquake is from the JMA catalog. Orange circles show seismic events shallower than 15 km based on JMA catalog depths from March 11, 2011, to December 31, 2011. The epicenters of events 4 and 11 are deeper than 15 km. The dashed circle indicates the approximate boundaries of the low-velocity zone resolved by Kato et al. (2013). Blue lines show the active faults (Research Group for Active Faults in Japan 1991)

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