The 1968 Hyūga-nada earthquake (Japanese: 1968年日向灘地震) occurred on April 1 at 09:42 local time. The earthquake had a magnitude of Mw 7.5, and the epicenter was located in Hyūga-nada Sea, off the islands of Kyushu and Shikoku, Japan. The magnitude of this earthquake was also given as Mjma 7.5. A tsunami was observed. There were 15 people reported injured. The intensity reached shindo 5 in Miyazaki and Kōchi.
This earthquake is the strongest event recorded in the Hyūga-nada Sea region. The maximum slip was estimated to be 4 m. It was estimated that, in the Hyūga-nada Sea region, earthquakes with magnitudes about 7.6 occur with a period of about 200 years, while earthquakes with magnitudes about 7.1 occur with a period of about 20 to 27 years. It has been pointed out that there is a tendency of occurrence of inland earthquakes in Kyushu before and after large interplate earthquakes in the Hyūga-nada Sea region.