A new explosion at a nuclear plant hit punch-drunk Japan Monday as it raced to avert a reactor meltdown after a quake-tsunami disaster that is feared to have killed more than 10,000 people.
Panic selling saw stocks close more than six percent lower on the Tokyo bourse on fears for the world's third-biggest economy, as power shortages prompted rolling blackouts and factories shut down in quake-hit areas.
As the nation struggled with the devastation wrought by the twin disasters of a shattered land and a surging sea, tales of terror, death and miraculous survival emerged.
But it was the fear of a nuclear disaster looming on top of the quake and tsunami that gripped the embattled nation as it struggled with a crisis described by Prime Minister Naoto Kan as the worst since World War II.
Japan has been battling to control two overheating reactors at the ageing Fukushima plant after the cooling systems were knocked out by Friday's 8.9-magnitude quake and the resulting tsunami that swallowed up whole towns.
A first explosion blew apart the building surrounding the plant's number-one reactor on Saturday but the seal around the reactor itself remained intact, officials said.
On Monday, shortly after Kan said the plant was still in an "alarming" state, a blast at its number-three reactor shook the facility and sent plumes of smoke billowing into the sky.
The plant's operator TEPCO said that six people were injured in the blast, which authorities said was probably a hydrogen explosion.
Chief government spokesman Yukio Edano said TEPCO reported that the reactor was probably undamaged and there was a low possibility of a major radiation leak at the plant, 250 kilometres (160 miles) northeast of Tokyo.
Radiation levels at the plant were "normal", the UN atomic watchdog IAEA said.
Later Monday the cooling system at the number two reactor failed, Jiji Press reported -- the sort of failure that preceded the explosions in the number one and three reactors.
Authorities have declared an exclusion zone within a 20 kilometre (12 mile) radius of the plant and evacuated 210,000 people.
The US nuclear-powered aircraft carrier Ronald Reagan, on a humanitarian mission to Japan, reportedly passed through a radioactive cloud from the plant and its crew received a month’s worth of radiation in about an hour.
There was no indication that any of the military personnel had experienced ill effects from the exposure, the New York Times reported citing unnamed government officials.
But the episode showed that the prevailing winds were picking up radioactive material from the crippled Fukushima plant, the newspaper noted.
Tsunami survivors who were able to outrun Friday's killer wave meanwhile recalled how they saw those behind them consumed by the torrent of mud and debris.
Miki Otomo's sister was one of the fortunate, though the image of victims violently swept away last week by the black tide of wrecked houses and cars near the hard-hit city of Sendai will be forever seared in her memory.
"My older sister was in a bus when the wave came behind them. The bus driver told everybody to get out of the bus and run," said Otomo, a mother of three teens who herself managed to escape the deadly wall of water in her car.
"My sister was able to get away but some people just couldn't run fast enough," she told AFP.
Otomo, whose home near Sendai was destroyed in the twin disasters, says she quickly piled her father and her dog in the car in her own desperate bid to survive.
"The tsunami wave was coming and I grabbed grandfather and our dog and drove. The wave was right behind me, but I had to keep zigzagging around obstacles and the water to get to safety."
Otomo is now staying at an evacuation centre in a local school with about 1,000 other exhausted survivors who cheated death.
A new tsunami scare triggered evacuations on the devastated northeast coast Monday after a large wave was spotted rolling in to shore, but authorities later lifted the alert.
With ports, airports, highways and manufacturing plants shut down, the government has predicted "considerable impact on a wide range of our country's economic activities".
Leading risk analysis firm AIR Worldwide said the quake alone would exact an economic toll estimated at between $14.5 billion and $34.6 billion (10 billion to 25 billion euros), without taking into account the effects of the tsunami.
Kan said in a televised national address Sunday that Japan was facing its worst crisis since the end of World War II -- which left the defeated country in ruins after two US atomic attacks forced its surrender.
The United Nations said a total of 590,000 people had been evacuated in the quake and tsunami disaster.
Japan's biggest ever earthquake sent waves of churning mud and debris racing over towns and farmland in the northeast, destroying everything in its path and reducing swathes of countryside to a swampy wasteland.
The police chief in badly hit Miyagi prefecture said the death toll was certain to exceed 10,000 in his region.
The national police agency said the confirmed death toll now stood at 1,597, but groups of hundreds of bodies were being found along the shattered coastline.
Many survivors were left without water, electricity, fuel or enough food, as authorities appeared overwhelmed by the monumental scale of the disaster.
Japan committed 100,000 troops -- about 40 percent of its armed forces -- to help survivors as the world rallied behind the disaster-stricken nation and the USS Ronald Reagan began ferrying in food.
Japan sits on the "Pacific Ring of Fire", and Tokyo is in one of its most dangerous areas, where three continental plates are slowly grinding against each other, building up enormous seismic pressure.
The immense force of Friday's quake has moved Honshu -- the main Japanese island -- by 2.4 metres (eight feet), the US Geological Survey said.