Reporting from Tokyo — A magnitude 7.1 aftershock struck northeastern Japan late Thursday night, prompting a brief tsunami warning for areas already ravaged by a March 11 earthquake and tsunami, according to the nation's meteorological agency.
The Japanese Meteorological Agency warned of tsunami heights of up to 6.6 feet in Miyagi prefecture and slightly less than 2 feet in nearby prefectures. The tsunami warning was lifted after 90 minutes.
Japanese media reported that the Onagawa nuclear plant in Miyagi lost two of three external power systems following the aftershock but still had power from one source.
No damage from Thursday's quake was detected at the Fukushima Daiichi nuclear plant crippled by last month's disaster, and Japanese television reported that workers had been evacuated without injury. In recent weeks, workers have labored to cool the reactors at the quake- and tsunami-battered Fukushima plant.