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

Fig. 1.

From: Spatial distribution of earthquakes off the east coast of the Kanto region along the Japan Trench deduced from ocean bottom seismographic observations and their relations with the aftershock sequence of the 2011 off the Pacific coast of Tohoku Earthquake

Fig. 1.

(a) Location map of the 2011 off the Pacific of Tohoku Earthquake with bathymetry. The red star denotes epicenter of the Mj 9.0 earthquake on March 11, 2011 and the yellow star represents the Mj 7.7 aftershock about 30 minutes after the mainshock. Grey stars and a white star show the other Mj 7.4 and Mj 7.5 aftershocks on March 11, 2011 and the Mj, 7.3 foreshock on March 9, 2011, 2 days before the mainshock. The rectangle depicts the area in (b). Broken lines and solid line denote contour intervals of 1 km water depth. Solid line corresponds to 7 km water depth. (b) The configuration of seismic stations used in this study. Yellow and green stars correspond to the Mj 7.7 aftershock on May 11, 2011 and the Mj 7.0 earthquake on May 8, 2008, respectively. Red and black crosses denote 50 OBS stations of the experiment in 2008. We deployed the red ones on May 19, 2008 and the black ones were installed in June 25–27, 2008. The 50 OBSs were recovered in October, 2008. Inverted triangles are the other 5 OBSs of another experiment from October 13, 2007 to June 25, 2008. Triangles show the routine seismic stations we used. White dots represent blast points of TNT dynamite used in a refraction experiment (Nakahigashi et al.). Broken and solid lines denote contour intervals of 1 km and 7 km water depth, respectively.

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