Hundreds of people are dead after one of the strongest earthquakes ever recorded struck Japan, triggering a devastating 10-metre-high tsunami along parts of the country's northeastern coastline.
The massive 8.9-magnitude earthquake struck on Friday afternoon local time, creating gigantic waves which swept away cars, boats, homes and people as the surging water overwhelmed coastal barriers.
Widespread fires burned out of control and Japan's nuclear industry was on alert as reactors shut down automatically as a safety precaution.
Millions of people are reported to be without electricity, airports are closed and public transport in Tokyo and other cities has come to a halt as Japan reels amid the twin devastations.
Police said 200 to 300 bodies have been found in the northeastern coastal city of Sendai where hundreds of buildings have collapsed. Japan's NHK television said the victims appeared to have drowned.
Police said another 88 were confirmed killed and 349 were missing.
Thousands of people living near a nuclear plant in Fukushima prefecture were ordered to evacuate after the reactor developing a cooling fault. Officials said the move was a precaution and there was no evidence of leaking radiation.
Meanwhile, countries around the Pacific basin are on tsunami alert amid warnings that a wall of water could completely wash over low-lying islands.
Ship swept away
Footage on NHK showed pictures of major tsunami damage in the north, with buildings being inundated by waves of water in Onahama city in Fukushima prefecture.
A ship carrying 100 people was swept away by the tsunami, Kyodo news agency reported.
The initial quake at 2:46pm was followed by a series of powerful aftershocks, including a 7.4-magnitude one about 30 minutes later.
A 6.6-magnitude earthquake struck the central and mountanous part of Japan early on Saturday.
Japan, which sits on the highly active "Ring of Fire," an arc of earthquake and volcanic zones that stretches around the Pacific Rim, is one of the most earthquake-ready nations in the world.
Many of its buildings are considered quake-proof while emergency services, citizens and schoolchildren regularly participate in earthquake drills.
"Japan is very well equipped to deal both with the initial tremors caused by an earthquake: buildings are systematically built with allowances for sway so that they are less likely to fall down," said Al Jazeera's Harry Fawcett.
"Also coastal cities have long had tsunami protection measures in place."
Japan's prime minister addressed the nation after the earthquake, saying major damage had been done but that help is on the way.
Al Jazeera's meteorologist explains Japan's quake
In a televised address, Naoto Kan said the government was making "every effort possible" to minimise damage.
"The earthquake has caused major damage in broad areas in northern Japan," he said.
"Some of the nuclear power plants in the region have automatically shut down, but there is no leakage of radioactive materials to the environment."
Shortly after the quake struck, the tsunami hit Sendai airport in the north-east.
Television footage showed people standing on the roof of the terminal building.
The tsunami roared over embankments in Sendai city, sweeping away cars, houses and farm equipment inland before reversing direction and carrying them out to sea. Flames shot from some of the houses, probably because of burst gas pipes.
A tsunami warning has been issued for the entire Pacific basin except mainland US and Canada, the US Pacific Tsunami Warning Centre said.
"An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines near the epicentre within minutes and more distant coastlines within hours," the centre said in a statement.
The International Federation of Red Cross and Red Crescent Societies warned that developing island nations could be devastated by the disaster.
"Our biggest concern is the Asia and Pacific region, where developing countries are far more vulnerable to this type of
unfolding disaster. The tsunami is a major threat," Paul Conneally, a spokesman for the federation, told the Reuters news agency in Geneva.
"At the moment, it is higher than some islands and could go right over them."
Among the countries for which a tsunami warning is in effect are: Russia, the Philippines, Indonesia, Papua New Guinea, Fiji, Mexico, Guatemala, El Salvador, Costa Rica, Nicaragua, Panama, Honduras, Chile, Ecuador, Colombia and Peru.
Meanwhile, a huge fire engulfed an oil refinery in Iichihara near Tokyo, where four million homes were said to be without electricity. Plumes of smoke rose from at least 10 locations in the city.
Military airplanes were flying over the worst-affected areas to assess the need for rescue efforts and 30 international search and rescue teams were prepared to go to Japan to provide assistance following the quake, the United Nations said.
Tokyo's metro and suburban trains were halted and airports were closed for parts of the day.
The quake that struck at 2:46pm was followed by a series of powerful aftershocks, including a 7.4-magnitude one about 30 minutes later.
Al Jazeera's Melissa Chan, reporting from Beijing, said tremors were felt as far away as the Chinese capital.
Several earthquakes have hit the region in recent days, including a 7.2-magnitude quake on Wednesday. Friday's quake struck at a depth of 24km, about 125km off the eastern coast, the country's meteorological agency said.
The earthquake's magnitude surpasses the 7.9 Great Kanto quake of 1923, which killed more than 140,000 people in the Tokyo area.