Fig. 22

a Stations of the ocean bottom seismometers array in the region off Ibaraki. The station intervals are about 6 km. The yellow triangles show the stations deployed on October 17, 2010, and the red triangles show those deployed on February 15, 2011. b, c S-wave velocities along the A-A’ and B-B’ lines. The red, orange, and green regions reflect layer 1, layer 2, and layer 3, respectively. We interpret the red and orange regions to be sedimentary layers, the green region to be Cretaceous sediment, and the blue region to be the upper crust, respectively. The black lines show the depth of the acoustic basement (between the orange and green regions) and the top of the upper crust (between the green and blue regions). Modified from Figs. 1 and 8 of Yamaya et al. (2021)