At least 50 people were hospitalized and 12 houses collapsed Tuesday when a major earthquake rocked southwestern Japan, state broadcaster NHK reported.
Authorities issued a tsunami alert after the 7.1-magnitude earthquake also knocked out power to thousands of households.
The tremor at 4:27 p.m. (7:27 a.m. GMT) on the island of Kyushu also measured at the highest possible level seven on Japan's own Shindo scale of shaking, the Japan Meteorological Agency said.
The tsunami could measure up to 1 meter (3 feet), the agency said.
Broadcaster NHK said that waves of up to that level may already have been recorded.
