The estimated death toll in Japan surpassed 10,000 Sunday, as authorities raced to combat the threat of multiple nuclear reactor meltdowns and hundreds of thousands of people struggled to find food and water.

The strongest recorded quake ever to hit Japan, as well the resulting powerful aftershocks and a ferocious tsunami that swallowed parts of the northeast, have killed more than 10,000 people in one prefecture alone.

The police chief told disaster relief officials that more than 10,000 people were killed in Miyagi, one of the three hardest hit states, police spokesman Go Sugawara told The Associated Press. That was an estimate — only 400 people have been confirmed dead in Miyagi, which has a population of 2.3 million.

According to officials, more than 1,800 people were confirmed dead, including 200 people whose bodies were found Sunday along the coast, and more than 1,400 were missing in Friday's disasters. Another 1,900 were injured.

Japan's prime minister said Sunday the earthquake and tsunami-stricken country is facing its worst national catastrophe since the Second World War.

As international rescue squads touched down on Sunday from Germany, Switzerland, Hungary and Taiwan, Prime Minister Naoto Kan implored citizens in a televised address to pull together to rebuild the devastated country.

''This is the worst crisis in the postwar history of 65 years,'' he said. ''All Japanese are now being tested on whether we can overcome the crisis, and I'm sure [we] will be able to overcome this crisis."

A man and child look out over destroyed homes in Sendai, northeastern Japan, on Saturday. (Kyodo/Reuters)

Japan has mobilized 100,000 troops to help pick through piles of debris and search for survivors. A tsunami spawned by Friday's 8.9-magnitude quake washed away vehicles and buildings, also leaving 1.4 million without running water and 2.5 million households without heat and electricity. Japanese officials believe the temblor was even stronger than the U.S. Geological Survey had initially measured, raising their calculations to 9.0 magnitude on Sunday.

To save energy, rolling blackouts moving along three hours at a time are to start on Monday, Kan said. It's the first time the Tokyo Electric Power Co. has had to take such measures in its 60-year history.

Etsuko Koyama was still searching for her daughter in the port city of Rikuzentakata, a community of about 20,000 people virtually wiped out by the tsunami. She had managed to escape the deluge in the third floor of her home, but lost grip of her child's hand and has still not found her.

"I haven't given up hope yet," a tearful Koyama told Japan's public broadcaster, NHK. "I saved myself, but I couldn't save my daughter."

Among the at least 1,800 people confirmed dead so far in Japan is one Canadian, Ottawa said. The government didn't release the victim's name and hometown, but media reports identified him as 76-year-old André Lachapelle from Saint-Jacques-de-Montcalm, Que. The minister of state for Foreign Affairs, Diane Ablonczy, said the department is in contact with the victim's family.

In the meantime, Foreign Affairs has issued a warning for Canadians to avoid non-essential travel to Miyagi, Ibaraki, Iwate, Fukushima and Aomori prefectures in northeast Japan. The U.S. State Department is also advising Americans to avoid going to Japan at this time, and France is warning its citizens to leave the Tokyo area, citing concerns about further earthquakes and possible radiation leaks from damaged nuclear power plants.

The scale of destruction in Japan was not yet known, but there were grim signs that the death toll could spike. At least 200 bodies had washed ashore in the northeast on Sunday. Another report said four whole trains had disappeared Friday and still had not been located. It's not known how many people were on the trains but the Kyodo news agency reported that several passengers and crew members were rescued.

Billions of dollars in damage

About 300,000 people have been evacuated across the country, Kyodo reported, and people were calling for bottled water, sleeping bags, tents, baby food and medical kits.

One of the few buildings not destroyed in Minamisanriku was the hospital, but seawater had reached four of its five floors. Hundreds of patients were stranded there waiting to be rescued, according to NHK.

The quake struck 125 kilometres off Japan's northeast coast. The majority of victims drowned in giant tsunami waves that swept 10 kilometres inland, created by the powerful temblor. Thousands of buildings and cars were washed away.

Kyodo reported on Sunday that Chief Cabinet Secretary Yukio Edano said the government would use some 200 billion yen ($2.44 billion Cdn) of contingency funds this month to pay for relief measures.

Officials are closely watching nuclear power plants after an explosion and secondary emergency at one of two nuclear plants damaged by the quake. The nuclear crisis rose on Sunday, when officials said it was likely that a partial meltdown was underway at one reactor in Fukushima.

The government had doubled in size the evacuation area around the Fukushima Daiichi nuclear power plant to a 20-kilometre radius.

Kyodo quoted the power company as saying four workers were hurt but their injuries were not life-threatening.

Smoke billows from an oil refinery plant on fire in Sendai on Saturday. (Koji Sasahara/Associated Press)

Police said between 200 and 300 bodies were found along the coast in Sendai, the biggest city in the area near the quake's epicentre. It has a population of one million and is relatively flat.

Kyodo, quoting the Fire and Disaster Management Agency and local police, said the coastal city of Rikuzentakata was "virtually destroyed" by a tsunami wave.

"Our initial assessment indicated that there has already been enormous damage," said Edano.

Many buildings, including an oil refinery plant in Sendai, were still burning Sunday. An out-of-control blaze burned through the night in the city of Kesennuma. NHK said local authorities had no way of tackling it.

Many aftershocks

Residents stranded in a building wait for rescue in Kesennuma, Japan, on Saturday morning. (Kyodo News/Associated Press)

There have been at least 150 powerful aftershocks since the quake struck. Among the strongest was a 6.6-magnitude tremor, which rattled Tokyo on Saturday. No tsunami warnings were issued and there were no reports of injuries.

In Hawaii, a two-metre-high wave hit parts of Maui and smaller waves hit Oahu and Kauai. In northern California, authorities were searching for a man believed swept out to sea. No significant wave action was felt in B.C.

Quake moved Honshu 2.5 metres

Japan is used to earthquakes and has instituted strict building codes and carries out frequent earthquake and tsunami drills. But the sheer intensity of Friday's disaster was such that even the best preparation could only mitigate the tragedy.

Officials said the initial quake was the most powerful one to hit the region in 1,200 years. The USGS says the force of the quake was so strong that Honshu — Japan's biggest island — was moved 2.5 metres to the east.

With files from The Associated Press