A day after responding to one of the worst earthquakes on record and a massive tsunami, the Japanese government sought to allay fears of a radioactive disaster at a nuclear power plant on the country's battered northeastern coast.
The outer walls of the Fukushima power plant's No. 1 reactor were blown off by a hydrogen explosion Saturday, leaving only a skeletal frame. Officials said four workers at the site received non-life-threatening injuries.
The inner container holding the reactor's fuel rods is not believed to be damaged, said Japan's Chief Cabinet Secretary Yukio Edano, and workers were cooling the facilities with seawater.
In a press conference shortly after the explosion, which left the facility shrouded in plumes of gray smoke, Edano explained that the reactor is contained within a steel chamber, which in turn is surrounded by a concrete and steel building. Although the explosion destroyed the building, it did not occur in the chamber.
"The escape of hydrogen mixed with the air between the chamber and the concrete-and-steel building and led to the explosion," Edano said.
"Tokyo Electric Power Co. has confirmed that the inner reactor is undamaged," he added. "There was no massive release of radiation."
Still, the reactor was already showing signs of a partial meltdown after Friday's magnitude 8.9 earthquake had prevented the plant 150 miles north of Tokyo from fully powering its water cooling system. Without it, the facility could overheat and explode, spewing radiation into the air.
Edano said experts were still determining what caused the blast.
"We are doing everything to ensure the safety of residents living nearby," said Edano, the government's chief spokesman. "I'm sure residents [living nearby] are feeling unease."
People were reportedly fleeing the surrounding area and Japanese television was urging people to cover their faces with wet towels and not to expose any skin to the potentially contaminated air. An evacuation zone was doubled to a 12-mile radius around the plant by Saturday evening.
"By taking all these appropriate measures, we would like to avoid any situation where any people's health is damaged," said Japanese Prime Minister Naoto Kan at a press conference. "This is an unprecedented disaster we're suffering."
Earlier in the day, workers had been racing to prevent the No. 1 reactor from over-heating by releasing accumulated vapor.
Officials of Japan's Nuclear and Industrial Safety Agency had insisted that the "slightly radioactive" emissions release posed no risk to people or the environment. Radiation levels inside the overheated reactor housing were 1,000 times normal, the agency said, but only eight times normal background at the plant's main gate. Experts explained that the steam carries low-level radiation that rapidly dissipates.
Japan relies on nuclear power for a third of its electricity and is said to require exacting safety standards for its plants.
The radiation scare comes on a day most of Japan was still trying to dig-out from an earthquake that's believed to have killed 1,700 people so far with countless still missing under rubble and muddy debris.
Japanese self-defense forces reportedly found 400 bodies in the seaside town of Rikuzentakata in Iwate prefecture. Television showed a rising tide rolling into the community, first filling the gaps between buildings before finally swallowing the city past its rooftops.
The force of the magnitude of Friday's quake, which seismologists said released 1,000 times the energy of the January 2010 earthquake in Haiti, broke the foundations under homes and buildings and opened chasms in fields and pavement, swallowing cars and shearing off sidewalks and driveways.
More than 100 aftershocks have jolted Japan since Friday's 2:46 p.m. temblor, including at least a dozen of magnitude 6 or higher, said Dave Applegate, a senior advisor at the U.S. Geological Survey.
The earthquake, centered just off the northeastern coastal city of Sendai, was the most powerful since a December 2004 quake and ensuing tsunami killed 230,000 people in Indian Ocean nations.
The havoc unleashed on Japan just ahead of Friday rush hour has left the nation mired in fear, suffering and hardship. Millions of people are without power, utility officials said, and they warned that outages would continue through the weekend, with rolling blackouts persisting for weeks.
Four trains carrying passengers along the coast at the time of the quake remain unaccounted for, East Japan Railway Co. reported. Television footage showed two passenger train carriages half submerged under water by the coast.
Only half of the hundreds of people reported trapped in elevators were rescued overnight, according to the Ministry of Land, Infrastructure, Transport and Tourism.
Key rail lines remained idle for a second day because of damaged track, tunnels and bridges. Service on Tokyo's vaunted subway system, the world's busiest with 8 million passengers per day, was sharply reduced pending safety inspections.
Limited air traffic resumed at major airports, including Tokyo's Narita International, but most were thronged by travelers marooned after major airlines suspended flights.
Steven Nia, a Los Angeles businessman heading for a flight home at the airport, said he slept the night in the terminal.
"I'm from California, so I recognize what an earthquake is, but I've never seen anything like this," Nia said.
Tokyo Bay, one of the busiest harbors in the world, was eerily quiet Saturday afternoon. Ships, barges and fishing boats sat idle in the still waters. The freeway across the bay was empty.
At Tokyo's railway station, hordes of people were making their way home after spending the night stranded in the capital.
Kenji Higuchi, 43, manager at the radio communications provider Japan Enix Co., said he spent the night monitoring and inspecting wireless base stations across Tokyo and slept in his office. He had to jostle for 10 minutes with throngs trying to board suburban trains just to get on the platform, he said.
"The images of destruction and flooding coming out of Japan are simply heartbreaking," President Obama told a news conference at the White House. He said the U.S. aircraft carrier Ronald Reagan was heading toward Japan to join the U.S. 7th Fleet's command ship, Blue Ridge, in the massive global relief effort.
Obama said he had spoken with the Japanese prime minister to extend condolences and "offered our Japanese friends whatever assistance is needed."
At least 45 countries scrambled disaster-relief teams, including 68 search-and-rescue units that were awaiting the Japanese government's direction on where to deploy, said Elisabeth Byrs of the U.N. Office for the Coordination of Humanitarian Affairs. A team of disaster responders sent to New Zealand by Tokyo after the Christchurch earthquake last month rushed back to help their devastated homeland.
The Defense Ministry said about 20,000 Self-Defense Forces troops, 190 aircraft and 25 vessels had been dispatched Saturday to the area around Sendai, where tsunami waves a day earlier churned whole neighborhoods into debris, crashing through homes and businesses and sweeping trains, trucks and cars into the moving mass of destruction.
Ministry officials were working with the Pentagon on plans to use U.S. naval forces to move 250 rescue vehicles into areas rendered unapproachable by waves that washed away roads and rail lines.
About 69,000 people were stranded at Tokyo Disneyland and Tokyo DisneySea because of road damage and idled mass transit. Theme park workers gave out blankets, heaters and coats to visitors forced to camp outside in 30-degree temperatures.
"Rations and supplies are just starting to reach emergency shelters," said Cabinet Secretary Yukio Edano, dressed in the light-blue jacket that identifies disaster-relief workers.
Images from the coastal city of Soma taken from a TV network helicopter showed trees that had been uprooted by the tsunami and then dragged back to shore when the waters receded.
Video taken over Kesennuma, in Miyagi prefecture, where the quake was most destructive, captured a Self-Defense Forces helicopter swooping low over a neighborhood to pluck a survivor from one of the few rooftops still above water.
In Iwanuma, survivors taking refuge on top of Minamihama Chuo Hospital waved flags and umbrellas to signal for help. All around them were water and the debris of buildings.
At Sendai airport, a small private jet appeared to have been carried by the rushing waters and left partly buried in waterlogged rubble. Most of the runway was under water.
Crews labored through the night to dig out trucks and cars that had fallen into chasms in roads and highways. At a Machida district shopping center in Tokyo, the ramp of a parking lot had collapsed, and workers with cranes were searching for people in the wreckage. One person pried from the rubble was unconscious and in critical condition.
"More than 90% of the houses in three coastal communities have been washed away by tsunami," a municipal official in the town of Futaba told the Kyodo News Agency. He said from his vantage point on the fourth floor of the town hall, "I see no houses standing."
Prime Minister Kan visited the stricken nuclear facility in a tour of the disaster areas. He vowed to "make whatever decisions need to be made" as he boarded a helicopter for the aerial tour.
Japan's nuclear facilities have survived many earthquakes. But the Kashiwazaki-Kariwa facility, the world's largest, was forced to close for two years in 2007 after being hit by an earthquake of greater force than the plant was designed to withstand. And Japan has a record of cover-ups when it comes to nuclear accidents. In 2007, the operators of the Shika plant acknowledged they had failed to report a 15-minute uncontrollable nuclear chain reaction eight years earlier. Another operator was forced to close 17 plants temporarily in 2003 after admitting it falsified safety inspection reports.
Japanese Finance Minister Yoshihiko Noda said the government would tap a contingency fund to cope with the massive damage, according to Kyodo News Agency.
Japan is already facing some of the highest public debt of any industrialized nation, running at about 200% of its annual economic output.
"To be honest I'm worried about the economy in the short term," said Kazu Hoshiai, 43, a Japan Airlines worker. "We are accustomed to earthquakes but not like this one."
Magnier and Demick reported from Tokyo and Williams from Los Angeles. Special correspondent Kenji Hall in Tokyo and Times staff writers Bruce Wallace and Brady MacDonald in Los Angeles and David Pierson in Beijing contributed to this report. Benjamin Haas in the Times' Beijing bureau also contributed to this report.