A strong earthquake of 5.9 magnitude struck off northern Japan's Aomori prefecture on Wednesday, in the second such incident in three days.
The quake originated at 30 kilometers (18.6 miles) deep, at a scale of four intensity out of a maximum of seven, at 11:52 p.m. local time (1452GMT), Kyodo News reported, citing the Japan Meteorological Agency.
There was no tsunami warning issued.
The German Research Center for Geosciences (GEOFON) measured the quake to be 6.0 magnitude and 48 kilometers (29.8 miles) deep.
Earlier late Monday night, at least 50 people were injured in a powerful 7.5 magnitude earthquake that struck northeastern Japan, with a warning of more tremors this week.
Authorities warned that the region could experience another quake of similar or greater intensity in the coming days, and the government ordered thousands of residents to prepare for evacuation.
