A magnitude 6.1 earthquake shook Japan southwest of Tokyo late Tuesday, far from last week's devastating and deadly earthquake and tsunami.

Tokyo's many highrise buildings shook frequently late Tuesday night, raising residents' fears after experts warned another big tremor could strike the quake-shocked country in the coming days.

"That prediction weighs heavy on people's minds each time the ground shakes," the CBC's Amber Hildebrandt reported from the Shibuya ward of Tokyo. "And when it's not the next big one, they wonder what the next quake might bring."

The focus of the latest quake was in the eastern part of Shizuoka prefecture and was estimated to be at a depth of 10 kilometres at 9:31 a.m. ET (10:31 p.m. local time). Shizuoka is 180 kilometres southwest of Tokyo.

The Chubu Electric Hamaoka Nuclear Power Plant in Shizuoka reported no irregularities and continued to operate after the quake, public broadcaster NHK said, and there were no immediate reports of damage or injuries.

The official death toll from Friday's quake and tsunami is now reported to be more than 3,300, with unofficial reports that some 10,000 people have died, and more than 15,000 people are unaccounted for.

Amid the destruction in the north and rising concern about the release of nuclear radiation from crippled reactors at Fukushima, shortages were affecting people elsewhere in the country as well.

Panic-buying sprees are leading to fears that hoarding may hurt the delivery of supplies to those who most need them. The CBC's John Northcott reported Tuesday from Tokyo that there are growing doubts about the government’s handling of the crisis.

"Japan is by most estimates one of the most organized societies on the planet," Northcott said, adding that "things have been different in the past few days.

"Concern and in some cases outright panic amongst members of the public after the tsunami and earthquakes have been exacerbated by the recent troubles at the nuclear plants.

"Many in Japan wonder whether the government is telling them the whole truth, or simply trying to mollify them and avoid public panic. Certainly panic is already taken place."

70-year-old rescued 4 days after quake

Northcott said he drove from Mito to Tokyo's Narita airport for three hours and didn’t see a single open gas station. "People are hoarding food as well."

He said Narita airport has stayed busy with people trying to leave the country.

"Without support, without gas and food, they’re finding Japan is not so hospitable these days."

Rescuers faced with overwhelming death and destruction still found surprises, however. A 70-year-old woman was located alive four days after the tsunami struck.

Osaka fire department spokesman Yuko Kotani said the woman was found inside her house, which had been washed off its site by the tsunami in northeastern Japan's Iwate prefecture. She was conscious but suffering from hypothermia and is being treated at a hospital.

On Monday, a man was found 15 kilometres offshore, floating on the remains of his house, which had been washed away from the city of Minamisoma.

Blankets sent by Canada

Canada's first shipment of relief supplies to Japan will leave Toronto's Pearson airport Wednesday morning, Foreign Affairs Minister Lawrence Cannon said Tuesday. At Japan's request, the aid will consist of approximately 25,000 wool blankets supplied from an emergency stockpile.

Cannon said Canada had offered other assistance as well, including "a 17-member disaster victim identification team, chemical, biological, radiological and nuclear technical expertise and equipment, Canadian Forces military assets to facilitate humanitarian relief efforts, relief stocks, and emergency medical and engineering capabilities."

“The Japanese government has specified the assistance it needs from the international community, and will continue to do so," said Cannon. "Canada stands ready to assist."

With files from Amber Hildebrandt, John Northcott and The Associated Press