Another large earthquake has struck Japan one month to the day after a devastating magnitude 9.0 earthquake and subsequent tsunami left 28,000 people dead or missing.

A tsunami warning and advisories were issued for parts of Japan's north-eastern coast after the 7.1 aftershock, but those have since been lifted.

The Japan Meteorological Agency measured the quake at a depth of about 10 kilometres, centred off the coast of the Fukushima prefecture, and there are reports of damage and injuries.

A tsunami warning was issued for Ibaraki prefecture and advisories for the Miyagi, Fukushima and Chiba prefectures as well as the Kujukuri and Sotobo areas.

Last Friday another powerful aftershock rocked an area of the country still reeling from March's earthquake and tsunami disaster, killing four people.

That quake, also measuring 7.1, hit the Miyagi prefecture and prompted Japanese authorities to warn that waves of up to two metres could hit the shoreline, but the tsunami warning was later cancelled.

Workers battling to contain a crisis at the stricken Fukushima nuclear plant were ordered to evacuate after today's aftershock, operator TEPCO said.

Officials say there have been no major irregularities and power has been restored to the crippled reactors.

The quake came only hours after Japan expanded the evacuation zone around the Fukushima plant because of high levels of accumulated radiation in the area.

A 20-kilometre exclusion zone has been in place around the plant since last month, sparking the worst nuclear crisis since Chernobyl.

But chief cabinet secretary Yukio Edano said villages and towns outside the 20-kilometre evacuation zone that have had more accumulated radiation would be evacuated.

Children, pregnant women and hospitalised patients should stay out of some areas 20 to 30km from the Fukushima complex, he added.

"We have made a new decision about evacuations based on data analysis of accumulated radiation exposure information," Mr Edano told a news conference.

"There is no need to evacuate immediately," he added, but said it would be desirable to proceed with the new evacuation over a one-month period.

On Monday Japan remembered the dead and missing from the March 11 disaster, with the country falling silent at precisely 2:46pm (local time).

In ruined villages along the north-east coast, survivors put their hands together in prayer and bowed their heads as once again an emergency siren sounded.

Japan's prime minister used the occasion to thank the world for offering help during the past month.

- ABC/Reuters