Tokyo - A strong earthquake with a preliminary magnitude of 5.7 jolted northern Japan on Tuesday, hours after an earlier quake triggered evacuation warnings in towns along the coast.
No tsunami warning was issued and there were no immediate reports of serious damage or injuries.
Japan's public broadcaster NHK showed live video footage which showed strong shaking in Aomori prefecture, about 700 kilometres north of Tokyo.
The quake was measured at depth of about 50km on the northeastern coast. Small waves were reported along the northern coast after an earlier quake forced thousands of residents to evacuate towns closest to the epicentre.
Towns along the northeastern coast of Japan were levelled in a devastating quake and tsunami in March 2011.
That disaster struck the Fukushima Daiichi plant, 220km north-east of Tokyo, sparking triple nuclear meltdowns, forcing more than 160 000 residents to flee nearby towns and contaminating water, food and air.
Tohoku Electric Power Co, which operates the Onagawa and Higashidori nuclear plants in nearby Miyagi and Aomori prefectures, told NHK it found no irregularities at the facilities after Tuesday's quake.
Earthquakes are common in Japan, one of the world's most seismically active areas.
Japan accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.
Reuters