Just before midnight, Japan time, north east Honshu got hit with the biggest “aftershock” yet, between 7.1 and 7.4.

At first there were tsunami warnings, but they were canceled when it was realized it was not the type of quake that would cause tsunami. But this latest quake puts another nuclear plant in trouble.

Onagawa nuke plant, in Miyagi Prefecture, was already struggling to keep itself cool using outside power. According to NHK this latest quake cut three of the two power lines running to the plant. There are some confusing reports as to how the plant is keeping its reactors cool; NHK says Onagawa is using power from one external electrical line. Reuters says Onagawa is running off back up generators.

The Japanese Nuclear and Industrial Safety Agency is rushing to confirm the status of the plant.