Prime Minister Yoshihide Suga said no casualties had so far been reported after the late-night quake, which did not trigger a tsunami warning.

"We have received reports of many injuries in the Fukushima and Miyagi regions. But so far we have not received any reports of deaths," he told an emergency cabinet meeting on Sunday morning.

The disaster agency said 74 injuries had been reported in the region and also around Tokyo, where the quake was felt strongly just after 11 pm on Saturday.

But local media counted at least 104 reported injuries, from broken bones to cuts from shattered glass.

No abnormalities were reported at the Fukushima nuclear plant, which melted down in the wake of the March 2011 quake that triggered a towering tsunami and killed more than 18,000 people.

Japan's meteorological agency said Saturday's quake, which hit at a depth of 60 kilometres (37 miles) in the Pacific off Fukushima, was considered an aftershock of the massive tremor nearly a decade ago.

"I was at home. I cannot even remember whether it was horizontal or vertical shaking. But it felt like it lasted for 30 seconds," Masami Nakai, a municipal official in Soma city in northern Fukushima, told AFP about Saturday's quake.

"The shaking was so strong I became truly afraid of my physical safety," he said.

No significant damage was reported but authorities were assessing the impact of a landslide on a highway, government spokesman Katsunobu Kato said, while aerial TV footage showed another landslide at a remote race circuit.

Kato warned residents about the possibility of strong aftershocks in the next week and further landslides due to heavy rain forecast.

"Particularly for the next two to three days, there might be very strong earthquakes," Kato said.

Emergency shelters

Water outages were affecting 4,800 households, Kato said, adding that health ministry staff and self-defense troops were heading to affected areas to deliver water.

Around 950,000 homes lost power throughout the region, but electricity had been restored in most areas by Sunday morning, according to a regional utility.

Kato said as of early Sunday more than 250 people were at 173 emergency shelters in Fukushima and surrounding regions, where social distancing measures have been put in place. Many may have since returned home, he added.

Pfizer, whose coronavirus vaccine is set to become the first to be approved in Japan later Sunday, has told the government that the quake did not affect facilities storing the jabs, Kato said.

Images posted online showed broken glass at a shop and items spilled off the shelves at a supermarket.

Tomoko Kobayashi, who works at a traditional inn in Fukushima's Minamisoma city, told Kyodo news agency that "the initial jolt felt more powerful than the one I experienced in the Great East Japan Earthquake" of 2011.

Renowned author Yu Miri, who also lives in Minamisoma, tweeted a photo of her home, showing books, potted plants and other belongings strewn across the floor.

"My house in Odaka, Minamisoma city is all messed up," she wrote.

"I hear the ground rumbling. And another quake," she tweeted about an aftershock.

The US Geological Survey registered the quake at a revised magnitude of 7.1 with a depth of 51 kilometers.

Japan sits on the Pacific "Ring of Fire", an arc of intense seismic activity that stretches through Southeast Asia and across the Pacific basin.

The country is regularly hit by quakes, and has strict construction regulations intended to ensure buildings can withstand strong tremors.

In September 2018, a powerful 6.6-magnitude quake rocked Hokkaido, triggering landslides, collapsing houses and killing more than 40 people.

Popular

Great Barrier Reef hit by record bleaching

Govt to undo latest curbs on personal imports

Middle East on edge as Israel and Iran trade threats