In September of 1990, a seismic refraction and reflection survey was conducted in the Japan Basin, in the northeastern part of the Japan Sea, as a part of the Japan-USSR joint expedition. Twenty-six ocean bottom seismometers (OBSs) were deployed on two 200-km long lines. Explosives and an airgun were fired as controlled seismic sources on the two mutually perpendicular lines. Airguns were also used as the source for the multi-channel reflection profiles.

The crustal structure deduced is that of a typical oceanic basin: the crustal thickness is about 8.5 km including 2 km of sediment. We obtained a more detailed crustal structure than that obtained previously. From the dense airgun shooting data, the crustal structure is well resolved to show layer 1A, layer 1B, layer 2A, 2B, 2C, layer 3, and the mantle. The crust basically consists of laterally homogeneous layers but the Moho deepens slightly westward. ¿ American Geophysical Union 1992