Fig. 18

Seismic velocity structure in and around the source area of the 2011 M 7.1 Miyagi–Oki intraslab earthquake. a Across-arc vertical cross-sections of S-wave velocity under central Tohoku along three lines: A–A', B–B', and C–C' in the inset map e. White stars in line A–A' and line C–C' denote the hypocenter of the 2011 M 7.1 event and the 2003 M 7.1 event, respectively. Solid and dashed black curves denote the upper surface of the Pacific slab and the Moho within it, respectively. White rectangle in a shows the area enlarged in b and c. b Across-arc vertical cross-sections of S-wave velocity and c Vp/Vs within the area outlined by the white rectangle in a. Black lines in A–A' and in B–B' show the fault plane of the 2011 M 7.1 event. d Schematic figure showing fault slips of the 2011 M 9.0 Tohoku–Oki earthquake (purple arrows) and the M 7.1 intraslab event (white arrows). e Map showing the aftershock distribution of the 2011 and 2003 intraslab events and the locations of the three lines, A–A', B–B', and C–C'. (After Nakajima et al. 2011)