A strong underwater earthquake measuring 5.1 struck late on Friday in the Pacific Ocean east of central Japan but there were no concerns of a tsunami, the Japan Meteorological Agency said.
The quake hit at 9:32 p.m. (1232 GMT) with its epicentre in the Pacific Ocean off the coast of Japan's Mie prefecture, the agency said.
The quake, which was 370 kilometres (230 miles) deep, was barely felt on land.
Minor tsunamis hit Japan late on Wednesday following one of the biggest earthquakes in recent times near the north-eastern Russian-ruled Kuril islands.
The earthquake, which Japanese meteorologists gave a revised magnitude of 7.9, triggered alerts stretching from Indonesian to California. With memories of the devastating 2004 Indian Ocean tsunami still fresh, some 130,000 people were urged to evacuate to higher ground for fear of seismic waves. But coastal residents were relieved when the earthquake did little more than flip over small boats.
Japan lies at the junction of four tectonic plates and endures about 20 percent of the world's most powerful earthquakes, which frequently jolt Tokyo and other major cities.