The 1946 Nankaido earthquake was unusual in its seismological perspective, with a rupture zone estimated from long-period geodetic data that was more than twice as large as that derived from shorter period seismic data. In the center of this earthquake rupture zone, scientists used densely deployed ocean bottom seismographs to detect a subducted seamount 13 kilometres (8 mi) thick by 50 kilometres (31 mi) wide at a depth of 10 kilometres (6 mi). Scientists propose that this seamount might work as a barrier inhibiting brittle seismogenic rupture.
The earthquake caused extensive damage, eventually destroying 36,000 homes in southern Honshū alone. The earthquake also caused a huge tsunami that took out another 2,100 homes with its. 5–6-metre (16–20-foot) waves.