A 7.1 magnitude earthquake hit northeast Japan Thursday, resulting in a tsunami warning.
The aftershock was one of the strongest since the March 11 earthquake which killed 25,000 people.
The recent quake was located near the site of the one that hit last month and caused no immediate disruption to the nuclear power plants in the area.
Heavy damage has been limited but power lines were out following the quake.
— The Associated Press contributed to this report.
