Fig. 1

Location map of this study. a Green inverted triangles, yellow squares, pink triangles, and blue diamonds represent TPG, GPS buoy, KPG, and DART stations, respectively. Small dots denote the aftershocks deduced from the ocean bottom seismographs (Obana et al. 2015). Gray contour lines indicate the coseismic slip distribution of the Tohoku-Oki earthquake (Iinuma et al. 2012) with 10 m intervals. Black dashed line represents the trench axis. b Enlarged map around the focal area. Black star shows the epicenter by Japan Meteorological Agency. Red, blue, and green CMT solutions are from GCMT, Lay et al. (2013) and Harada et al. (2013), respectively. Gray CMT solution denotes the 1967 m_b 4.7 earthquake (Seno and Gonzalez 1987). c The vertical cross-section along the A-B line in a. Aftershocks within the dashed rectangle in a are shown. Black curved line is the plate boundary (Ito et al. 2005). Schematic image of the intraplate bending stress state is also shown (red: down-dip compressional stress, blue: extensional stress). The thick line denotes the approximate location of the stress neutral plane