Sendai, Japan ? A strong aftershock ripped through northeastern Japan, killing two, injuring dozens and piling misery on a region still buried under the rubble of last month’s devastating tsunami.

The quake late Thursday was the strongest tremor since the March 11 jumbo and did some damage, but it appeared to have spared the area’s nuclear power plants. The Fukushima Dai-ichi complex — where workers have been frantically trying to cool overheated reactors since they lost cooling systems last month — reported no new abnormalities. Other facilities switched to diesel generators after the 7.1-magnitude quake knocked out power to much of the area.

Many people in the area have lived without water and electricity for nearly a month, and the latest tremor sunk more homes into blackness: In total, around 3.6 million households — about 60 percent of residents in the area — were dark today, said Souta Nozu, a spokesman for Tohoku-Electric Power Co., which serves northern Japan.