Authorities in Japan are scrambling to provide relief to survivors of the earthquake and tsunami, which may have killed more than 10,000 people, and to prevent a nuclear meltdown.
The Fukushima nuclear reactors are in danger of meltdown
The Japanese government said on Sunday that cooling systems had failed at two reactors at Fukushima Daiichi nuclear plant belonging to Tokyo Electric Power (TEPCO).
"There is the possibility of an explosion in the third reactor, as in the case of the first reactor," Chief Cabinet Secretary Yukio Edano told a televised press conference, but he added that reactor three could withstand it as reactor one did a day earlier.
Radiation levels around the plant have reportedly risen above the safety limit, but Edano said there was no immediate threat to the health of nearby residents.
Officials said 190 people were within a 10-kilometer (6.2-mile) radius of the nuclear plant when levels rose and 22 people were confirmed to have been exposed to radiation.
'Biggest crisis since World War II'
Friday's 8.9-magnitude earthquake was the largest ever recorded in Japan. Strong aftershocks continued to shake the country on Sunday. The earthquake and the devastating tsunami it triggered are believed to have killed thousands with 10,000 people unaccounted for in the small port town of Minamisanriku. That town was essentially wiped off the map by the 10-meter (33-foot) waves.
The immense force of the quake moved Honshu - the main Japanese island - 2.4 metres (8 feet), the US Geological Survey said.
The tsunami caused massive devastation in Japan
"The earthquake, tsunami and the nuclear incident have been the biggest crisis Japan has encountered in the 65 years since the end of World War II," Japan's Prime Minister Naoto Kan said in a televised address.
"Whether we Japanese can overcome this crisis depends on each of us," he added.
Kan said there would be rolling power outages beginning on Monday and urged citizens to conserve energy. Almost two million households are already without power, with 1.4 million without running water.
Reports say around 300,000 people have fled the devastation caused by the quake and the tsunami. More than 1,400 emergency camps have been set up in five Japanese provinces.
Kan maintained, however, that the ongoing nuclear emergency was not another Chernobyl in the making.
"Radiation has been released into the air, but there are no reports that a large amount was released," he said. "This is fundamentally different from the Chernobyl accident."
Engineers were in the process of releasing another dose of radioactive steam from a second reactor on Sunday, according to top government spokesman Yukio Edano.
"We are doing two things at the same time - venting air out of the reactor and supplying water into the reactor," Edano said. "Radiation released in the process is low enough not to affect people's health."
Technicians are using sea water to try and cool down the reactor and prevent a meltdown. Experts claim the use of this method shows how desperate the situation is, as sea water damages the reactors to such an extent that they can not be turned back on.
The world's worst nuclear disaster happened in Chernobyl, Ukraine
Japanese news reports said the cooling water levels in the reactor have dropped so much that up to three meters of the fuel rods were exposed, making overheating a real threat.
Acting on assumptions
Asked in a news conference whether meltdowns had occurred, Edano said "we are acting on the assumption that there is a high possibility that one has occurred" in the plant's number one reactor. Contrary to earlier statements, he added that there had been no meltdown in the number three reactor.
Energy officials in Japan rated Saturday's nuclear accident a four on the international nuclear and radiological event scale, which goes from zero to seven. The rating denotes a "nuclear accident with local consequences."
The 1979 Three-Mile Island accident in the United States was given a five-rating, and the 1986 Chernobyl meltdown was given the worst rating of seven.
Officials were distributing iodine to people living near the reactor. Iodine helps protect the body from exposure to radioactive material.
The International Atomic Energy Agency said Sunday that Japan had informed it that it had declared the first, or lowest, state of emergency at Onagawa nuclear power plant in Miyagi prefecture, the hardest hit by the earthquake and tsunami.
"The alert was declared as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant," the IAEA said. The reactors at the plant were however "under control."
Japan has made an official appeal for more rescue teams from around the world
The United States was sending two rescue teams and a pair of nuclear energy experts to Japan. The search teams from Fairfax, Virginia and Los Angeles include more than 140 personnel, sniffer dogs and equipment to help with rescue efforts.
Germany's Disaster Relief Agency (THW) has sent 44 men and women to help with search and rescue efforts.
The United Nations put 30 disaster response teams on alert to help Japan if needed.
"Our experts are in close contact with the disaster management in Japan, and, so far, Japan's national resources are fully engaged in the response," said Elisabeth Byrs, a spokeswoman for the UN Office for the Coordination of Humanitarian Affairs.
Meanwhile, German Environment Minister Norbert Röttgen told German public broadcaster ARD that the disaster in Japan begged the question if nuclear energy was in fact manageable.
"I think we cannot escape that debate anymore," he said, adding that the use of alternative energy sources must be sped up.
"It's a given that we want to get away from nuclear energy," he pledged.
Author: Nicole Goebel, Holly Fox (AFP, dpa, Reuters)
Editor: Sean Sinico