Two people have died and dozens were injured after a strong aftershock ripped through north-eastern Japan, piling misery on a region still buried under the rubble of last month's devastating tsunami.
The quake late on Thursday was the strongest tremor since the March 11 disaster and did some damage, but it did not generate a tsunami and 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 retained a connection to the grid or 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% of residents in the area - were dark on Friday, said Souta Nozu, a spokesman for Tokyo Electric Power Co, which serves northern Japan.
Five conventional plants in the area were out, and it was not clear when power would be restored, he said.
Matsuko Ito, who has been living in a shelter in the small north-eastern city of Natori since the tsunami, said there was no getting used to the terror of being awoken by shaking.
"I was almost as scared as much as last time," said the 64-year-old while smoking a cigarette outside. "It's enough."
Thursday's quake initiated a tsunami warning of its own, but it was later cancelled.
Two people were killed, fire department spokesman Junichi Sawada said. A 79-year-old man died of shock and a woman in her 60s was killed when power was cut to her oxygen tank. More than 130 people were injured, according to the national police agency.
The tremor's epicentre was in about the same location as the original 9.0-magnitude tremor, off the eastern coast and about 40 miles from Sendai, an industrial city on the eastern coast, according to the U.S. Geological Survey.