AUTHORITIES are scrambling to contact more than 1000 Australians in Japan, with fears more than 200 are stuck in the areas most devastated by Friday's quake and tsunami.
Grave concerns are held for a Melbourne man missing in the Sendai region, an area pummeled by the 10m wave, the Department of Foreign Affairs said last night.
Melbourne mother Mary Briffa said she was in a panic after not hearing from her son Jason since Friday's tsunami.
The 25-year-old was working there as an English teacher.
He had been due to return to Australia just weeks ago, but decided to stay longer in Japan.
"It's very stressful, the waiting," Ms Briffa said last night.
"He always writes on his blog, but he hasn't done that since the ninth (of March). It is not like him."
As the number of Australians known to be in the hardest hit areas was revised up to 223 last night, Prime Minister Julia Gillard said communications had been a major problem. Electricity is cut to about 2.5 million homes. About 2551 Australians are registered as being in Japan, with the Government already confirming the safety of 1675.
DFAT has been swamped with 6500 calls in Canberra from worried relatives.
Ms Gillard said she'd been "truly shocked" by the scale of the unfolding disaster.
"We've all seen images now of buildings swaying, of walls of water hitting buildings, of the rubble and devastation that has left townships that have literally been eradicated from the face of the earth," she said.
She said Australia needed to be prepared for the possibility Australians had been killed.
A team of about 75 Australian search-and-rescue workers and sniffer dogs were due to arrive in stricken Japan last night many just after arriving back home from a massive search and recovery effort in Christchurch. Ms Gillard said she had been reassured about their fatigue levels.
"We're putting a big burden on their shoulders . . . but it's what they're trained to do, it's what they want to do," she said.
The Government has deployed extra consular staff to the region to help stranded Australians.
Ms Gillard said a backlog of Australians had been cleared from Narita airport near Tokyo, but it was expected more would turn up today attempting to flee the country.
Four consular officials will work at the airport to help Australians escape the area.
Ms Gillard also warned Australians to avoid the area near the Fukushima No.1 nuclear plant as authorities battled to keep a major nuclear meltdown at bay.
A second explosion was feared there last night.
Ms Gillard said she had been advised that Australia was not at risk from the possible nuclear meltdown at Fukushima, but Foreign Affairs Minister Kevin Rudd demanded urgent nuclear briefings from Japan on the matter.
Australia stands ready to provide further support to Japan, including nuclear advice, medical teams and assistance with disaster identification.
The C-17 aircraft used to carry Australian search and rescue crews into Japan could remain stationed in the region to help transport supplies around the disaster zone.