Tokyo (CNN) -- The return of electricity spread slowly Saturday across northern Japan, where hundreds were injured and tens of thousands remained without power after one of the strongest aftershocks following last month's devastating earthquake struck the region.
Nearly 250,000 were still waiting for their lights to come on as crews rushed to repair damaged water and gas lines.
At least 283 people were injured by Thursday's 7.1-magnitude aftershock alone. It was blamed for two deaths; intial reports indicated a few more deaths, though the causes of those could not be directly tied to the aftershock.
Japan is still reeling for the the massive magnitude 9.0 earthquake that slammed the nation on March 11, sparking a nuclear crisis. The death told from that quake and the resulting tsunami stood at 12,921 on Saturday, with nearly 15,000 people still missing, according to Japan's National Police Agency.
Communities across northern Japan planned to hold solemn commemorations Monday, including moments of silence to mark one month since the disaster struck.
A Japanese researcher said Friday that residents in eastern Japan, including Tokyo, can expect more such aftershocks in the coming months.
"We should not be surprised to have magnitude-7 level aftershocks even a year afterward anywhere as wide as east Japan in the wake of such mega-quake of magnitude 9," said Satoko Oki of the Earthquake Research Institute of Tokyo University.
Meanwhile, a key transportation hub in Sendai -- one of the areas worst hit by last month's quake -- is preparing to start up operations again. Limited commercial service at the airfield south of the city and near the coast will be restored April 13, authorities and airlines said.
"As a result of efforts aiding recovery by the Japanese Ministry of Land, Infrastructure, Transport and Tourism, the self-defense force, the U.S. military and other organizations, the airport is being opened sooner than originally expected," Japanese airline ANA said in a statement.
ANA said it will make three "relief" flights daily to and from Tokyo's Haneda airport, while rival Japan Airlines said it will operate three flights a day into the airport from Tokyo and Osaka.
The re-opening of the airfield will bring relief to the region, which is still without express train service. Many roads and dozens of railroad lines and stations also were knocked out by the disaster.
Currently, the airlines believe that, at the earliest, they will be able to restore regular service by the end of May.