The 1946 Nankai earthquake (南海地震 Nankai jishin) was a great earthquake in Nankaidō, Japan. It occurred on December 21, 1946 at 04:19 JST (December 20, 19:19 UTC). The earthquake measured between 8.1 and 8.4 on the moment magnitude scale, and was felt from Northern Honshū to Kyūshū.