News reports say another strong quake hit Northern Japan, just about the same area as the big one one month ago.
NHK video footage of Sendai shows a big flash of light on the horizon and the city lights went off. My Twitter TL says it is likely that an electricity substation had short circuit or something. Other tweets say that Onagawa Nuke Power Plant, another working power plant in the area, has taken additional safety measures and it is OK.
Again, according to my TL, mobile phones in Sendai area are not working perfectly now, because of the carriers' restrictions rather than the physical damage or power problem of the base stations. As long as the power recovers, service is likely to be restored. Currently, data connection is relatively better.