On December 21, 1946, a significant seismic event occurred off the coast of Nankaidō, Japan, registering a magnitude of 8.1 Mw. The earthquake struck at a depth of approximately 25 kilometers, leading to substantial undersea disturbances that generated a powerful tsunami. The waves impacted various coastal towns, devastating infrastructure and communities in a matter of minutes. Alongside the loss of life, with over 1,300 reported casualties, the subsequent destruction of homes and essential services created widespread displacement and humanitarian challenges.

In the aftermath, rescue and recovery efforts were swiftly mobilized, as government agencies and local organizations worked to provide assistance to those affected. Many communities faced prolonged periods of rebuilding due to the extensive damage inflicted on residential and commercial structures. The event served as a grim reminder of Japan's geographical positioning along the Pacific Ring of Fire, where tectonic activity is prevalent, raising awareness about disaster preparedness and response strategies.

Additionally, the scale of the disaster prompted important discussions about the necessity for improved building codes and regulations in earthquake-prone areas. This particular earthquake and tsunami eventually became a subject of research in seismology and disaster management, leading to a stronger emphasis on early warning systems and public education regarding natural disasters in Japan and around the world.