A 5.5-magnitude earthquake struck off the northeast coast of Japan on Saturday, the United States Geological Survey (USGS) reported.
The quake hit at depth of 40 kilometres (25 miles) at 11:59 pm (1459 GMT Saturday), about 123 kilometres east of the northern city of Sendai, the USGS said. There were no immediate reports of damage.
A powerful 7.3-magnitude undersea quake off the northeast coast earlier this month triggered a one-metre-high tsunami but no reports of fatalities.
In March last year a devastating earthquake and tsunami in the same area left some 19,000 people dead or missing and crippled the Fukushima nuclear power plant in the world's worst atomic disaster in 25 years.