Bathymetric map of the Shikoku Basin and surrounding areas based on multi-beam bathymetry. Red lines show the positions of three seismic lines across the basin. Red arrows show the position of the Kinan Escarpment (KE). Black asterisks and a north-south (NS) line indicate the OBS positions and a seismic refraction profile by Nishizawa et al. (2006). P3 and P9 are the locations of the two-ship experiments by Murauchi et al. (1968).