The Kyodo news service quoted the Nuclear and Industrial Safety Agency as saying that the latest quake, which is believed to be the aftershock of the previous catastrophic one, did not affect the already troubled Fukushima Daiichi and Daini nuclear power plants, and the ongoing reconstruction work there.
No tsunami warnings were issued following the quakes, it added.
Among them, a quake with a preliminary magnitude of 6.0 shook mainly Fukushima Prefecture at 7:12 hours local time.
The quake measured 7 in Iwaki, and 4 in several locations in Fukushima, Miyagi and Ibaraki prefectures. It was followed by additional quakes, one of which also measured more than 5 in Fukushima Prefecture and lower than 5 in Ibaraki Prefecture, the agency added.
