Tokyo was rocked by a massive tremor on Tuesday, compounding the fears of residents already gripped by concerns that nuclear radiation from a damaged power plant could reach the city.

According to the Japan Meteorological Society, the quake struck the Shizuoka-ken Tobu region southwest of Tokyo at approximately 10:30 p.m. local time. It rumbled from a relatively shallow depth of 10 kilometres, with a magnitude of 6.0.

Freelance journalist Chris Johnson had been in Tokyo, but headed for the Shizuoka region on Tuesday amidst fears radiation from a damaged nuclear plant in the country's northeast was headed for the capital.

"People have been fleeing to this area thinking that they would get away from that active fault line, get away from the earthquakes and get away from the radiation possibilities," Johnson told CTV in a telephone interview from his hotel room in Shizuoka prefecture, less than 100 kilometres southwest of Tokyo.

"So right now we're thinking: 'Where can we go in Japan?'," he added, describing the doubts among those who joined the exodus from Tokyo earlier in the day.

"A lot of people left the city, including myself," Johnson said, explaining that many assumed the area around Japan's iconic Mount Fuji was safe.

"It's in a totally different part of the country than the other ones have been," he said.

Tokyo residents had been told Tuesday that the danger posed by radiation leaking from the Dai-ichi nuclear plant in the Fukushima prefecture some 240 kilometres northeast of the city was minimal.

But that didn't stop many from fleeing the densely populated metropolis, and did little to calm the panic among those who chose to stay.

Many stores have run out of radios, flashlights, candles, fuel cans, sleeping bags and other survival gear. Shops have also been cleared staple foods.

"People are getting angry when they go to stores now and can't see very basic things like bread or rice and that's in Tokyo," Johnson said, describing the panic buying he witnessed amongst people rushing to stock up on basic necessities.

Flights Diverted

Although the damage from the quake and tsunami that struck on March 11 was centred on four prefectures in the country's northeast, the repercussions continue to be felt around the country.

In addition to rolling power blackouts, train service has been disrupted and there are long lines of travellers at the country's international airports.

Responding to the huge delays at Narita International Airport, which is located about 65 kilometres northeast of Tokyo, Germany's Lufthansa airline announced on Tuesday that it will now divert its daily flights to the Japanese capital.

The German carrier's daily flight from Frankfurt to Tokyo will instead land at Nagoya, while flights from Munich will be rerouted to Osaka.

Lufthansa spokesperson Thomas Jachnow said the changes will remain in effect until Sunday, at least.

"From the other cities we'll be able to offer a more stable flight schedule, which is also a preventive measure," Jachnow said.

With files from The Associated Press