TOKYO — Japan was rattled by a strong aftershock and tsunami warning Thursday night nearly a month after a devastating earthquake and tsunami flattened the northeastern coast.
Announcers on Japan's public broadcaster NHK told coastal residents to run to higher ground and away from the shore. Within a few hours, the tsunami warning and advisories were lifted.
The Japan meteorological agency issued a tsunami warning for a wave of up to 6 feet (two meters) after the magnitude-7.4 aftershock. The warning had been issued for a coastal area already torn apart by last month's tsunami, which is believed to have killed some 25,000 people and has sparked an ongoing crisis at a nuclear power plant.
Officials at the tsunami-ravaged Fukushima Dai-ichi nuclear plant said there's no immediate sign of new problems caused by the aftershock. Plant operator Tokyo Electric Power Co. said it evacuated two workers there and seven at a sister plant to the south that was not badly damaged.
Officials say Thursday's aftershock hit 16 miles (25 kilometers) under the water and off the coast of Miyagi prefecture. The quake that preceded last month's tsunami was a 9.0-magnitude.
Buildings as far away as Tokyo shook for about a minute.
In Ichinoseki, inland from Japan's eastern coast, buildings shook violently, knocking items from shelves and toppling furniture, but there was no heavy damage to the buildings themselves. Immediately after the quake, all power was cut. The city went dark, but cars drove around normally and people assembled in the streets despite the late hour.
Paul Caruso, a geophysicist at the U.S. Geological Survey in Golden, Colo., said Thursday's quake struck at about the same location and depth as the March 11 quake. It's the strongest of the more than 1,000 aftershocks that have been felt since, except for a 7.9 aftershock that day.
The USGS said the aftershock struck off the eastern coast 40 miles (65 kilometers) from Sendai and 70 miles (115 kilometers) from Fukushima. It was about 205 miles (330 kilometers) from Tokyo.
A Pacific Tsunami Warning Center evaluation of the quake said an oceanwide tsunami was not expected. However, it noted quakes of that strength can cause waves that are destructive locally.
Th tremor happened just as Japanese police raced Thursday to find thousands of missing bodies before they completely decompose along a stretch of tsunami-pummeled coast that has been largely off-limits because of a radiation-leaking nuclear plant.
Nearly a month after a 9.0-magnitude earthquake generated the tsunami along Japan's northeastern coast, more than 15,000 people are still missing. Many of those may have been washed out to sea and will never be found.
In the days just after the March 11 disaster, searchers gingerly picked through mountains of tangled debris, hoping to find survivors. Heavier machinery has since been called in, but unpredictable tides of radiation from the Fukushima Dai-ichi nuclear complex have slowed progress and often forced authorities to abandon the search, especially within a 12-mile (20-kilometer) evacuation zone around the plant.
Officials now say there's not much time left to find and identify the dead, and are ramping up those efforts.
"We have to find bodies now as they are decomposing," said Ryoichi Tsunoda, a police spokesman in Fukushima prefecture, where the plant is located. "This is a race against time and against the threat of nuclear radiation."
More than 25,000 people are believed to have been killed, and 12,600 are confirmed dead. There is expected to be some overlap in the dead and missing tolls because not all the bodies have been identified.
Recent progress at the plant — which the tsunami flooded — appears to have slowed the release of radiation into the ocean. Early Wednesday, technicians there plugged a crack that had been gushing contaminated water into the Pacific. Radiation levels in waters off the coast have fallen dramatically since then, though contaminated water continues to pool throughout the complex, often thwarting work there. A floating island storage facility — which officials hope will hold the radioactive water — arrived at the port near Tokyo on Thursday and will soon head to Fukushima.
After notching a rare victory, technicians began pumping nitrogen into the chamber of reactor Thursday to reduce the risk of a hydrogen explosion.
Three hydrogen blasts rocked the complex in the days immediately following the tsunami, which knocked out vital cooling systems. An internal report from March 26 by the U.S. Nuclear Regulatory Commission warned such explosions could occur again and recommended adding nitrogen. The gas will be injected into all three of the troubled reactors over the next six days.
Plant operator Tokyo Electric Power Co. has been under intense pressure to get the crisis under control, and the company's president was hospitalized last week amid reports he'd had a breakdown. Masataka Shimizu spent eight days in the hospital with dizziness and high blood pressure, but was back at work Thursday, according to spokesman Takashi Kurita.
Radiation in the air, soil and water in Fukushima prefecture has also been declining since Saturday, and Tsunoda said a small team resumed the search there a day later. But the operation dramatically increased on Thursday, when 330 police and 650 soldiers fanned out, wearing white protective gear from head to toe. They are concentrating on areas between six and 12 miles (10 and 20 kilometers) from the plant — all of which are within the zone evacuated because of radiation fears.
Chief Cabinet Secretary Yukio Edano said the government is studying ways to allow residents in the evacuation zones to return briefly to check on their homes and retrieve any possession that may be left, but they would have to be escorted and wear protective gear.
"I understand that many residents have eagerly waiting for a chance to go back, but this is not something we can approve just to mark one month from the disaster," Edano said. "If we provide an opportunity, we cannot allow anyone to go anytime."
The government has said it may expand the evacuation zone due to concerns about longer-term radiation exposure as the crisis wears on.
Iitate village, about 25 miles (40 kilometers) from Fukushima Dai-ichi, said Thursday it is advising pregnant women and children under 3 to go to hotels farther from the plant. The International Atomic Energy Agency last month reported high levels of contamination in Iitate's soil. Village officials did not say why they are just now telling some people to leave.
On the fringes of Minami Soma, a city that straddles the no-go zone and was flattened in the crush of water, teams patrolled deserted streets Thursday. Packs of dogs caked with mud and the searchers were the only beings roaming the emptied streets.
One area inside the evacuation area seemed frozen in time: Doors swung open, bicycles lined the streets, a lone taxi sat outside the local train station.
One body was pulled out of the rubble Thursday morning.
"We just got started here this morning, so we expect there will be many more," said one officer, who requested anonymity because he was not authorized to speak to the media.
More than 1,000 people are missing in the city alone.
"I believe the search will continue until they find as many of the missing as they can, but we fear many of the missing were washed out to sea or are buried under rubble," said Takamitsu Hoshi, a city official. "We haven't been able to do much searching at all because of the radiation concerns. It was simply too dangerous."
Last weekend, U.S. and Japanese troops conducted a massive, all-out search of coastal waters, finding about 70 bodies over three days. While such operations haven't stopped completely, they'll be severely limited going forward. The death toll for the 2004 Asian tsunami includes tens of thousands of bodies that were never found, likely sucked out to sea.
Meanwhile, the U.S. State Department confirmed the death of Montgomery Dickson — the second American confirmed killed in the disaster. It gave no other details.
While some progress has been made at the nuclear complex in recent days, radiation spewed over the past few weeks continues to travel — in trace amounts — farther afield. On Thursday, one South Korean province allowed schools to cancel classes after rain containing small amounts of radiation fell in the area. The contamination posed no health threat, according to the prime minister's office.
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