TOKYO — A powerful aftershock 16 miles off northeastern Japan late Thursday disrupted power supplies to two nuclear facilities and complicated efforts to contain a month-long emergency at a third, the Fukushima Daiichi nuclear power station.
The quake — which authorities said killed two people, injured more than 130 and left tens of thousands of homes without power — struck an area still digging out from the wreckage of the devastating March 11 tsunami.
Japanese television interrupted programming Thursday night to flash warnings of another tsunami, but the alert was later lifted.
The U.S. Geological Survey estimated the magnitude of Thursday’s quake at 7.1, down from an initial estimate of 7.4. The March 11 quake that spawned the tsunami was magnitude-9.0.
Fire department spokesman Junichi Sawada said today that a 79-year-old man died of shock and that a woman in her 60s died when power was cut to her oxygen tank.
Blackouts were seen throughout the northeastern coastal region of Honshu, Japan’s main island, and two nuclear facilities lost much of their external power supply.
Electrical troubles at the Onagawa nuclear power station, north of Sendai, and a nuclear reprocessing plant farther north, near a U.S. air base in Aomori prefecture, did not appear to pose any risk of catastrophic failure, as happened last month at the Fukushima Daiichi plant. But they highlighted the vulnerability of Japan’s nuclear archipelago, a network of reactors and other facilities that have been a pillar of the country’s energy policy since the 1970s.
Seeking to calm an already traumatized public, Tetsuro Fukuyama, the deputy chief Cabinet secretary, told a late-night news conference that adequate power had been restored to both the Onagawa plant and the reprocessing facility using generators or undamaged power lines and that the plants pose no danger.
The quake came just hours after a rare bit of good news: a successful operation to avert a possible explosion at a reactor at Fukushima Daiichi by injecting nitrogen. Earlier blasts at the six-reactor plant led to the worst nuclear disaster since Chernobyl.
In Tokyo, a little more than 200 miles south of the epicenter of Thursday’s quake, buildings swayed for more than a minute. Japan has experienced hundreds of aftershocks since the March 11 quake, but until Thursday, none had exceeded a 6.6.
This aftershock was stronger than the 6.9-magnitude Kobe earthquake in 1995 that led to more than 5,000 deaths, with 310,000 evacuated.
A spokesman for Tokyo Electric Power Co. said at a news conference that it had no information of further damage to the Fukushima Daiichi plant and that Thursday’s quake would not interrupt efforts to bring the facility under control. But the temblor added another headache for workers engaged in an already risky and technically difficult operation to cool overheating and to plug leaks that have allowed radiation to seep into the air and sea.
